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Greek_alphabet.txt Phi.txt
Greek alphabet Phi
The Greek alphabet has been used to write the Greek language since the 8th century BC. It was derived from the earlier Phoenician alphabet,[http://www.arcalog.com/wp-content/uploads/2014/04/Near-Eastern-Chronology-and-the-development-of-the-Greek-Alphabet.pdf The Development of the Greek Alphabet within the Chronology of the ANE] (2009), Quote: "Naveh gives four major reasons why it is universally agreed that the Greek alphabet was developed from an early Phoenician alphabet.1 According to Herodutous “the Phoenicians who came with Cadmus... brought into Hellas the alphabet, which had hitherto been unknown, as I think, to the Greeks.”2 The Greek Letters, alpha, beta, gimmel have no meaning in Greek but the meaning of most of their Semitic equivalents is known. For example, ‘aleph’ means ‘ox’, ‘bet’ means ‘house’ and ‘gimmel’ means ‘throw stick’.3 Early Greek letters are very similar and sometimes identical to the West Semitic letters.4 The letter sequence between the Semitic and Greek alphabets is identical. (Naveh 1982)" and was the first alphabetic script to have distinct letters for vowels as well as consonants. It is the ancestor of the Latin and Cyrillic scripts. Apart from its use in writing the Greek language, in both its ancient and its modern forms, the Greek alphabet today also serves as a source of technical symbols and labels in many domains of mathematics, science and other fields.

In its classical and modern forms, the alphabet has 24 letters, ordered from alpha to omega. Like Latin and Cyrillic, Greek originally had only a single form of each letter; it developed the letter case distinction between upper-case and lower-case forms in parallel with Latin during the modern era.

Sound values and conventional transcriptions for some of the letters differ between Ancient Greek and Modern Greek usage, because the pronunciation of Greek has changed significantly between the 5th century BC and today. Modern and Ancient Greek use different diacritics. The traditional orthography, which is used for Ancient Greek and sometimes for Modern Greek, has many diacritics, such as accent marks for pitch accent ("polytonic"), the breathing marks for the presence and absence of the initial sound, and the iota subscript for the final historical sound. In standard Modern Greek spelling, orthography has been simplified to the monotonic system, which uses only two diacritics: the acute accent and diaeresis.

Letters 

Sound values 

In both Ancient and Modern Greek, the letters of the Greek alphabet have fairly stable and consistent symbol-to-sound mappings, making pronunciation of words largely predictable. Ancient Greek spelling was generally near-phonemic. For a number of letters, sound values differ considerably between Ancient and Modern Greek, because their pronunciation has followed a set of systematic phonological shifts that affected the language in its post-classical stages. 

Among consonant letters, all letters that denoted voiced plosive consonants (/b, d, g/) and aspirated plosives (/pʰ, tʰ, kʰ/) in Ancient Greek stand for corresponding fricative sounds in Modern Greek. The correspondences are as follows:

Among the vowel symbols, Modern Greek sound values reflect the radical simplification of the vowel system of post-classical Greek, merging multiple formerly distinct vowel phonemes into a much smaller number. This leads to several groups of vowel letters denoting identical sounds today. Modern Greek orthography remains true to the historical spellings in most of these cases. As a consequence, the spellings of words in Modern Greek are often not predictable from the pronunciation alone, while the reverse mapping, from spelling to pronunciation, is usually regular and predictable.

The following vowel letters and digraphs are involved in the mergers:

Modern Greek speakers typically use the same, modern, sound-symbol mappings in reading Greek of all historical stages. In other countries, students of Ancient Greek may use a variety of conventional approximations of the historical sound system in pronouncing Ancient Greek.

Digraphs and letter combinations 

Several letter combinations have special conventional sound values different from those of their single components. Among them are several digraphs of vowel letters that formerly represented diphthongs but are now monophthongized. In addition to the three mentioned above () (and in some cases the ancient Greek υι, for example ), there is also , pronounced /u/. The Ancient Greek diphthongs ,  and  are pronounced [av], [ev] and [iv] respectively in voicing environments in Modern Greek (or alternatively as [af], [ef] and [if] respectively in devoicing environments). The Modern Greek consonant combinations  and  stand for [b] and [d] (or [mb] and [nd]) respectively;  stands for [dz] and  stands for [t͡s]. In addition, both in Ancient and Modern Greek, the letter , before another velar consonant, stands for the velar nasal [ŋ]; thus  and  are pronounced like English . (Analogously to  and ,  is also used to stand for [g].) There are also the combinations  and .

Diacritics 

In the polytonic orthography traditionally used for ancient Greek, the stressed vowel of each word carries one of three accent marks: either the acute accent (), the grave accent (), or the circumflex accent ( or ). These signs were originally designed to mark different forms of the phonological pitch accent in Ancient Greek. By the time their use became conventional and obligatory in Greek writing, in late antiquity, pitch accent was evolving into a single stress accent, and thus the three signs have not corresponded to a phonological distinction in actual speech ever since. In addition to the accent marks, every word-initial vowel must carry either of two so-called "breathing marks": the rough breathing (), marking an sound at the beginning of a word, or the smooth breathing (), marking its absence. The letter rho (ρ), although not a vowel, also carries a rough breathing in word-initial position. If a rho was geminated within a word, the first ρ always had the smooth breathing and the second the rough breathing  (ῤῥ) leading to the transiliteration rrh.

The vowel letters  carry an additional diacritic in certain words, the so-called iota subscript, which has the shape of a small vertical stroke or a miniature  below the letter. This iota represents the former offglide of what were originally long diphthongs,  (i.e. /aːi, ɛːi, ɔːi/), which became monophthongized during antiquity.

Another diacritic used in Greek is the diaeresis (), indicating a hiatus.

In 1982, a new, simplified orthography, known as "monotonic", was adopted for official use in Modern Greek by the Greek state. It uses only a single accent mark, the acute (also known in this context as tonos, i.e. simply "accent"), marking the stressed syllable of polysyllabic words, and occasionally the diaeresis to distinguish diphthongal from digraph readings in pairs of vowel letters. The polytonic system is still conventionally used for writing Ancient Greek, while in some book printing and generally in the usage of conservative writers it can still also be found in use for Modern Greek.

Although it is not a diacritic the Comma has in a similar way the function as a silent letter in a handful of Greek words, principally distinguishing  (ó,ti, "whatever") from  (óti, "that").Nicolas, Nick. "[http://www.tlg.uci.edu/~opoudjis/unicode/punctuation.html Greek Unicode Issues: Punctuation]". 2005. Accessed 7 Oct 2014.

Romanization 

There are many different methods of rendering Greek text or Greek names in the Latin script. The form in which classical Greek names are conventionally rendered in English goes back to the way Greek loanwords were incorporated into Latin in antiquity. In this system,  is replaced with , the diphthongs  and  are rendered as  and  (or ) respectively; and  and  are simplified to  and  respectively. In modern scholarly transliteration of Ancient Greek,  will usually be rendered as , and the vowel combinations  as  respectively. The letters  and  are generally rendered as  and ;  as either  or ; and word-initial  as .

For Modern Greek, there are multiple different transcription conventions. They differ widely, depending on their purpose, on how close they stay to the conventional letter correspondences of Ancient Greek-based transcription systems, and to what degree they attempt either an exact letter-by-letter transliteration or rather a phonetically based transcription. Standardized formal transcription systems have been defined by the International Organization for Standardization (as ISO 843),  by the United Nations Group of Experts on Geographical Names,  by the Library of Congress,  and others.

History 

Origins 

During the Mycenaean period, from around the 16th century to the 12th century BC, Linear B was used to write the earliest attested form of the Greek language, known as Mycenaean Greek. This writing system, unrelated to the Greek alphabet, last appeared in the 13th century BC. In the late 9th century BC or early 8th century BC, the Greek alphabet emerged. The period between the times of the two writing systems, from which no Greek texts are attested, is called the Greek Dark Ages. The Greeks adopted the alphabet from the earlier Phoenician alphabet, one of the closely related scripts used for the West Semitic languages. When the Phoenician alphabet was adopted for writing Greek, certain Phoenician consonant letters were adopted to write vowels. This feature makes Greek the first alphabet in the narrow sense, as distinguished from the abjads used for the Semitic languages, which only have letters for consonants.

Greek initially took over all of the 22 letters of Phoenician. Five of them were reassigned to denote vowel sounds: the glide consonants (yodh) and (waw) were used for [i] (Ι, iota) and [u] (Υ, upsilon) respectively; the glottal stop consonant ('aleph) was used for [a] (Α, alpha); the pharyngeal (ʿayin) was turned into [o] (Ο, omicron); and the letter for (he) was turned into [e] (Ε, epsilon). A doublet of waw was also borrowed as a consonant for [w] (Ϝ, digamma). In addition, the Phoenician letter for the emphatic glottal (heth) was borrowed in two different functions by different dialects of Greek: as a letter for /h/ (Η, heta) by those dialects that had such a sound, and as an additional vowel letter for the long (Η, eta) by those dialects that lacked the consonant. Eventually, a seventh vowel letter for the long (Ω, omega) was introduced.

Greek also introduced three new consonant letters for its aspirated plosive sounds and consonant clusters: Φ (phi) for, Χ (chi) for and Ψ (psi) for. In western Greek variants, Χ was instead used for and Ψ for The origin of these letters is a matter of some debate.

Three of the original Phoenician letters dropped out of use before the alphabet took its classical shape: the letter Ϻ (san), which had been in competition with Σ (sigma) denoting the same phoneme /s/; the letter Ϙ (qoppa), which was redundant with Κ (kappa) for /k/, and Ϝ (digamma), whose sound value /w/ dropped out of the spoken language before or during the classical period.

Greek was originally written predominantly from right to left, just like Phoenician, but scribes could freely alternate between directions. For a time, a writing style with alternating right-to-left and left-to-right lines (called boustrophedon, literally "ox-turning", after the manner of an ox ploughing a field) was common, until in the classical period the left-to-right writing direction became the norm. Individual letter shapes were mirrored depending on the writing direction of the current line.

Archaic variants 

There were initially numerous local variants of the Greek alphabet, which differed in the use and non-use of the additional vowel and consonant symbols and several other features. A form of western Greek native to Euboea, which among other things had Χ for /ks/, was transplanted to Italy by early Greek colonists, and became the ancestor of the Old Italic alphabets and ultimately, through Etruscan, of the Latin alphabet. Athens used a local form of the alphabet until the 5th century BC; it lacked the letters Ξ and Ψ as well as the vowel symbols Η and Ω. The classical 24-letter alphabet that became the norm later was originally the local alphabet of Ionia; this was adopted by Athens in 403 BC under archon Eucleides and in most other parts of the Greek-speaking world during the 4th century BC.

Letter names 

When the Greeks adapted the Phoenician alphabet, they took over not only the letter shapes and sound values, but also the names by which the sequence of the alphabet could be recited and memorized. In Phoenician, each letter name was a word that began with the sound represented by that letter; thus ʾaleph, the word for "ox", was used as the name for the glottal stop, bet, or "house", for the sound, and so on. When the letters were adopted by the Greeks, most of the Phoenician names were maintained or modified slightly to fit Greek phonology; thus, ʾaleph, bet, gimel became alpha, beta, gamma.

The Greek names of the following letters are more or less straightforward continuations of their Phoenician antecedents. Between Ancient and Modern Greek they have remained largely unchanged, except that their pronunciation has followed regular sound changes along with other words (for instance, in the name of beta, ancient /b/ regularly changed to modern /v/, and ancient /ɛː/ to modern /i/, resulting in the modern pronunciation vita). The name of lambda is attested in early sources as  besides ;  in Modern Greek the spelling is often , reflecting pronunciation. Similarly, iota is sometimes spelled  in Modern Greek ( is conventionally transcribed  word-initially and intervocalically before back vowels and). In the tables below, the Greek names of all letters are given in their traditional polytonic spelling; in modern practice, like with all other words, they are usually spelled in the simplified monotonic system.

In the cases of the three historical sibilant letters below, the correspondence between Phoenician and Ancient Greek is less clear, with apparent mismatches both in letter names and sound values. The early history of these letters (and the fourth sibilant letter, obsolete san) has been a matter of some debate. Here too, the changes in the pronunciation of the letter names between Ancient and Modern Greek are regular.

In the following group of consonant letters, the older forms of the names in Ancient Greek were spelled with , indicating an original pronunciation with -ē. In Modern Greek these names are spelled with .

The following group of vowel letters were originally called simply by their sound values as long vowels: ē, ō, ū, and. Their modern names contain adjectival qualifiers that were added during the Byzantine period, to distinguish between letters that had become confusable. Thus, the letters  and , pronounced identically by this time, were called o mikron ("small o") and o mega ("big o") respectively. The letter  was called e psilon ("plain e") to distinguish it from the identically pronounced digraph , while, similarly, , which at this time was pronounced, was called y psilon ("plain y") to distinguish it from the identically pronounced digraph .

Some dialects of the Aegean and Cypriot have retained long consonants and pronounce and; also,  has come to be pronounced in Cypriot. 

Letter shapes 

Like Latin and other alphabetic scripts, Greek originally had only a single form of each letter, without a distinction between uppercase and lowercase. This distinction is an innovation of the modern era, drawing on different lines of development of the letter shapes in earlier handwriting.

The oldest forms of the letters in antiquity are majuscule forms. Besides the upright, straight inscriptional forms (capitals) found in stone carvings or incised pottery, more fluent writing styles adapted for handwriting on soft materials were also developed during antiquity. Such handwriting has been preserved especially from papyrus manuscripts in Egypt since the Hellenistic period. Ancient handwriting developed two distinct styles: uncial writing, with carefully drawn, rounded block letters of about equal size, used as a book hand for carefully produced literary and religious manuscripts, and cursive writing, used for everyday purposes.  The cursive forms approached the style of lowercase letter forms, with ascenders and descenders, as well as many connecting lines and ligatures between letters.

In the 9th and 10th century, uncial book hands were replaced with a new, more compact writing style, with letter forms partly adapted from the earlier cursive. This minuscule style remained the dominant form of handwritten Greek into the modern era. During the Renaissance, western printers adopted the minuscule letter forms as lowercase printed typefaces, while modelling uppercase letters on the ancient inscriptional forms. The orthographic practice of using the letter case distinction for marking proper names, titles etc. developed in parallel to the practice in Latin and other western languages.

Derived alphabets 

The Greek alphabet was the model for various others:

* The Latin alphabet, together with various other ancient scripts in Italy, adopted from an archaic form of the Greek alphabet brought to Italy by Greek colonists in the late 8th century BC, via Etruscan
* The Gothic alphabet, devised in the 4th century AD to write the Gothic language, based on a combination of Greek and Latin models 
* The Glagolitic alphabet, devised in the 9th century AD for writing Old Church Slavonic
* The Cyrillic script, which replaced the Glagolitic alphabet shortly afterwards

It is also considered a possible ancestor of the Armenian alphabet, which in turn influenced the development of the Georgian alphabet. 

Other uses 

Use for other languages 

Apart from the daughter alphabets listed above, which were adapted from Greek but developed into separate writing systems, the Greek alphabet has also been adopted at various times and in various places to write other languages. For some of them, additional letters were introduced.

Antiquity 

* Most of the alphabets of Asia Minor, in use c. 800–300 BC to write languages like Lydian and Phrygian, were the early Greek alphabet with only slight modifications – as were the original Old Italic alphabets.
* Some Paleo-Balkan languages, including Thracian. For other neighboring languages or dialects, such as Ancient Macedonian, isolated words are preserved in Greek texts, but no continuous texts are preserved.
* The Greco-Iberian alphabet was used for writing the ancient Iberian language in parts of modern Spain.
* Gaulish inscriptions (in modern France) used the Greek alphabet until the Roman conquest
* The Hebrew and Aramaic text of the Bible was written in Greek letters in Origen's Hexapla.
* The Bactrian language, an Iranian language spoken in what is now Afghanistan, was written in the Greek alphabet during the Kushan Empire (65–250 AD). It adds an extra letter  for the sh sound.
* The Coptic alphabet adds eight letters derived from Demotic. It is still used today, mostly in Egypt, to write Coptic, the liturgical language of Egyptian Christians. Letters usually retain an uncial form different from the forms used for Greek today.

Middle Ages 

* An 8th-century Arabic fragment preserves a text in the Greek alphabet.
* An Old Ossetic inscription of the 10-12c AD found in Arxyz, the oldest known attestation of an Ossetic language.
* The Old Nubian language of Makuria (modern Sudan) adds three Coptic letters, two letters derived from Meroitic script, and a digraph of two Greek gammas used for the velar nasal sound.
* Various South Slavic dialects, similar to the modern Bulgarian and Macedonian languages, have been written in Greek script. The modern South Slavic languages now use modified Cyrillic alphabets.

Early modern 

* Turkish spoken by Orthodox Christians (Karamanlides) was often written in Greek script, and called Karamanlidika.
* Tosk Albanian was often written using the Greek alphabet, starting in about 1500. The printing press at Moschopolis published several Albanian texts in Greek script during the 18th century. It was only in 1908 that the Monastir conference standardized a Latin orthography for both Tosk and Gheg. Greek spelling is still occasionally used for the local Albanian dialects (Arvanitika) in Greece.
* Aromanian (Vlach) has been written in Greek characters. There is not yet a standardized orthography for Aromanian, but it appears that one based on the Romanian orthography will be adopted.
* Gagauz, a Turkic language of the northeast Balkans.
* Surguch, a Turkic language spoken by a small group of Orthodox Christians in northern Greece.
* Urum or Greek Tatar.
* Pomak language in Western Thrace.

In mathematics and science 

Greek symbols are used as symbols in mathematics, physics and other sciences.  Many symbols have traditional uses, such as lower case epsilon (ε) for an arbitrarily small positive number, lower case pi (π) for the ratio of the circumference of a circle to its diameter, capital sigma (Σ) for summation, and lower case sigma (σ) for standard deviation.

Astronomy 

Greek letters are used to denote the brighter stars within each of the eighty-eight constellations. In most constellations the brightest star is designated Alpha and the next brightest Beta etc. For example, the brightest star in the constellation of Centaurus is known as Alpha Centauri. For historical reasons, the Greek designations of some constellations begin with a lower ranked letter.

International Phonetic Alphabet 

Several Greek letters are used as phonetic symbols in the International Phonetic Alphabet (IPA).  Several of them denote fricative consonants; the rest stand for variants of vowel sounds. The glyph shapes used for these letters in specialized phonetic fonts is sometimes slightly different from the conventional shapes in Greek typography proper, with glyphs typically being more upright and using serifs, to make them conform more with the typographical character of other, Latin-based letters in the phonetic alphabet. Nevertheless, in the Unicode encoding standard, the following three phonetic symbols are considered the same characters as the corresponding Greek letters proper:

On the other hand, the following phonetic letters have Unicode representations separate from their Greek alphabetic use, either because their conventional typographic shape is too different from the original, or because they also have secondary uses as regular alphabetic characters in some Latin-based alphabets, including separate Latin uppercase letters distinct from the Greek ones.

The symbol in Americanist phonetic notation for the voiceless alveolar lateral fricative is the Greek letter lambda , but  in the IPA. The IPA symbol for the palatal lateral approximant is , which looks similar to lambda, but is actually an inverted lowercase y.

Additionally, Unicode contains ẟ that is not used in IPA. Unicode 8.0 will add Ꭓ, Ꞵ, ꞵ, Ꞷ, and ꞷ for use in German and African languages.

Use as numerals 

Greek letters were also used to write numbers. In the classical Ionian system, the first nine letters of the alphabet stood for the numbers from 1 to 9, the next nine letters stood for the multiples of 10, from 10 to 90, and the next nine letters stood for the multiples of 100, from 100 to 900. For this purpose, in addition to the 24 letters which by that time made up the standard alphabet, three otherwise obsolete letters were retained or revived: digamma  for 6, koppa  for 90, and a rare Ionian letter for [ss], today called sampi , for 900. This system has remained in use in Greek up to the present day, although today it is only employed for limited purposes such as enumerating chapters in a book, similar to the way Roman numerals are used in English. The three extra symbols are today written as ,  and  respectively. To mark a letter as a numeral sign, a small stroke called keraia is added to the right of it.

Use in naming student fraternities and sororities 

In North America, many college fraternities and sororities are named with combinations of Greek letters, and are hence also known as "Greek letter organizations". This naming tradition was initiated by the foundation of the Phi Beta Kappa Society, in 1776. 

Glyph variants 

Some letters can occur in variant shapes, mostly inherited from medieval minuscule handwriting. While their use in normal typography of Greek is purely a matter of font styles, some such variants have been given separate encodings in Unicode.

* The symbol ϐ ("curled beta") is a cursive variant form of beta (β).  In the French tradition of Ancient Greek typography, β is used word-initially, and ϐ is used word-internally.
* The letter epsilon can occur in two equally frequent stylistic variants, either shaped \epsilon\,\! ('lunate epsilon', like a semicircle with a stroke) or \varepsilon\,\! (similar to a reversed number 3). The symbol ϵ (U+03F5) is designated specifically for the lunate form, used as a technical symbol.
* The symbol ϑ ("script theta") is a cursive form of theta (θ), frequent in handwriting, and used with a specialized meaning as a technical symbol.
* The symbol ϰ ("kappa symbol") is a cursive form of kappa (κ), used as a technical symbol.
* The symbol ϖ ("variant pi") is an archaic script form of pi (π), also used as a technical symbol.
* The letter rho (ρ) can occur in different stylistic variants, with the descending tail either going straight down or curled to the right. The symbol ϱ (U+03F1) is designated specifically for the curled form, used as a technical symbol.
* The letter sigma, in standard orthography, has two variants: ς, used only at the ends of words, and σ, used elsewhere. The form ϲ ("lunate sigma", resembling a Latin c) is a medieval stylistic variant that can be used in both environments without the final/non-final distinction.
* The capital letter upsilon (Υ) can occur in different stylistic variants, with the upper strokes either straight like a Latin Y, or slightly curled. The symbol ϒ (U+03D2) is designated specifically for the curled form, used as a technical symbol.
* The letter phi can occur in two equally frequent stylistic variants, either shaped as \textstyle\phi\,\! (a circle with a vertical stroke through it) or as \textstyle\varphi\,\! (a curled shape open at the top). The symbol ϕ (U+03D5) is designated specifically for the closed form, used as a technical symbol.

Computer encodings 

For the usage in computers, a variety of encodings have been used for Greek online, many of them documented in RFC 1947.

The two principal ones still used today are ISO/IEC 8859-7 and Unicode. ISO 8859-7 supports only the monotonic orthography; Unicode supports both the monotonic and polytonic orthographies.

ISO/IEC 8859-7 

For the range A0–FF (hex) it follows the Unicode range 370–3CF (see below) except that some symbols, like ©, ½, § etc. are used where Unicode has unused locations. Like all ISO-8859 encodings it is equal to ASCII for 00–7F (hex).

Greek in Unicode 

Unicode supports polytonic orthography well enough for ordinary continuous text in modern and ancient Greek, and even many archaic forms for epigraphy. With the use of combining characters, Unicode also supports Greek philology and dialectology and various other specialized requirements. Most current text rendering engines do not render diacritics well, so, though alpha with macron and acute can be represented as U+03B1 U+0304 U+0301, this rarely renders well: .

There are two main blocks of Greek characters in Unicode. The first is "Greek and Coptic" (U+0370 to U+03FF). This block is based on ISO 8859-7 and is sufficient to write Modern Greek. There are also some archaic letters and Greek-based technical symbols.

This block also supports the Coptic alphabet. Formerly most Coptic letters shared codepoints with similar-looking Greek letters; but in many scholarly works, both scripts occur, with quite different letter shapes, so as of Unicode 4.1, Coptic and Greek were disunified. Those Coptic letters with no Greek equivalents still remain in this block (U+03E2 to U+03EF).

To write polytonic Greek, one may use combining diacritical marks or the precomposed characters in the "Greek Extended" block (U+1F00 to U+1FFF).

Combining and letter-free diacritics 

Combining and spacing (letter-free) diacritical marks pertaining to Greek language:

Encodings with a subset of the Greek alphabet 

IBM code pages 437, 860, 861, 862, 863, and 865 contain the letters ΓΘΣΦΩαδεπστφ (plus β as an alternate interpretation for ß). Phi (uppercase Φ, lowercase  or ; , pheî,; modern , fi,; English: ) is the 21st letter of the Greek alphabet. In Ancient Greek, it represented an aspirated voiceless bilabial plosive, which was the origin of its usual romanization as "ph". In modern Greek, it represents a voiceless labiodental fricative and is correspondingly romanized as "f". Its origin is uncertain but it may be that phi originated as the letter qoppa and initially represented the sound before shifting to Classical Greek.  In traditional Greek numerals, phi has a value of 500 () or  (). The Cyrillic letter Ef (Ф, ф) descends from phi.

Phi is also used as a symbol for the golden ratio and on other occasions in math and science. This use is separately encoded as the Unicode glyph ϕ. The modern Greek pronunciation of the letter is sometimes encountered in English (as) when the letter is being used in this sense. 

 Use as a symbol 

The lower-case letter φ (or often its variant, ϕ) is often used to represent the following:
* Magnetic flux in physics
*The golden ratio \tfrac{1 + \sqrt{5}}{2} \approx  ... in mathematics, art, and architecture.
*Euler's totient function φ(n) in number theory; also called Euler's phi function.
*The cyclotomic polynomial functions Φn(x) of algebra.
*In algebra, group or ring homomorphisms
* In probability theory,  is the probability density function of the normal distribution.
* In probability theory,  is the characteristic function of a random variable X.
*An angle, typically the second angle mentioned, after θ (theta).  Especially:
**The argument of a complex number.
**The phase of a wave in signal processing.
**In spherical coordinates, mathematicians usually refer to phi as the polar angle (from the z-axis).  The convention in physics is to use phi as the azimuthal angle (from the x-axis).
**One of the dihedral angles in the backbones of proteins in a Ramachandran plot
**Internal or effective angle of friction.
*The work function of a surface, in solid-state physics.
*A shorthand representation for an aromatic functional group in organic chemistry.
*The fugacity coefficient in thermodynamics.
*The ratio of free energy destabilizations of protein mutants in phi value analysis.
*In cartography and navigation, latitude.
*In combustion engineering, fuel–air equivalence ratio. The ratio between the actual fuel air ratio to the stoichiometric fuel air ratio.
*A sentence in first-order logic.
*The Veblen function in set theory
*Porosity in geology and hydrology.
*Strength (or resistance) reduction factor in structural engineering, used to account for statistical variabilities in materials and construction methods.
*The symbol for a voiceless bilabial fricative in the International Phonetic Alphabet (using the straight line variant character)
*In economics, this is usually an additive term.
*In flight dynamics, the roll angle.
*In philosophy, φ is often used as shorthand for a generic act. (Also in upper-case.)
*In perceptual psychology, the phi phenomenon is the apparent motion caused by the successive viewing of stationary objects, such as the frames of a motion picture.
*In lexical-functional grammar, the function that maps elements from the c-structure to the f-structure.

The upper-case letter Φ is used as a symbol for:
*The golden ratio conjugate −0.618... in mathematics.
*The magnetic flux and electric flux in physics, with subscripts distinguishing the two.
*The cumulative distribution function of the normal distribution in mathematics and statistics.
*In philosophy, Φ is often used as shorthand for a generic act. (Also in lower-case.)
*The number of phases in a power system in electrical engineering, for example 1Φ for single phase, 3Φ for three phase.
*A common symbol for the parametrization of a surface in vector calculus.
*In Lacanian algebra, Φ stands for the imaginary phallus and also represents phallic signification; -Φ stands in for castration. 
The diameter symbol in engineering, ⌀, is often incorrectly referred to as "phi". This symbol is used to indicate the diameter of a circular section; for example, "⌀14" means the diameter of the circle is 14 units.

Computing 

In Unicode, there are multiple forms of the phi letter:

In ordinary Greek text, the character U+03C6 φ is used exclusively, although this character has considerable glyphic variation, sometimes represented with a glyph more like the representative glyph shown for U+03C6 (φ, the “loopy” form) and less often with a glyph more like the representative glyph shown for U+03D5 (ϕ, the “straight“ form).

Because Unicode represents a character in an abstract way, the choice between glyphs is purely a matter of font design. While some Greek typefaces, most notably "Porson" typefaces (used widely in editions of classical Greek texts), have a "stroked" glyph in this position (), most other typefaces have "loopy" glyphs. This goes for the "Didot" (or "apla") typefaces employed in most Greek book printing (), as well as for the "Neohellenic" typeface often used for ancient texts ().

It is necessary to have the stroked glyph available for some mathematical uses, and U+03D5 GREEK PHI SYMBOL is designed for this function. Prior to Unicode version 3.0 (1998), the glyph assignments in the Unicode code charts were the reverse, and thus older fonts may still show a loopy form \varphi at U+03D5.

For use as a phonetic symbol in IPA, Unicode has a separate codepoint U+0278, LATIN SMALL LETTER PHI, because in this use only the stroked glyph is considered correct. It typically appears in a form adapted to a Latin typographic environment, with a more upright shape than normal Greek letters and with serifs at the top and bottom.

In HTML/XHTML, the upper- and lower-case phi character entity references are Φ (Φ) and φ (φ), respectively.

In LaTeX, the math symbols are \Phi (\Phi\,\!), \phi (\phi\,\!), and \varphi (\varphi\,\!).

The Unicode standard also includes the following variants of phi and phi-like characters:
Phi Φ %5Cphi Φι Phi (Greek) Phi (letter) Varphi
varphi 5cphi phi letter phi greek φι φ phi
phi
WikipediaEntity
Phi
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