Number theory
While the word "algorithm" goes back only to certain readers of al-Khwārizmī, careful descriptions of methods of solution are older than proofs: such methods (that is, algorithms) are as old as any recognisable mathematics—ancient Egyptian, Babylonian, Vedic, Chinese—whereas proofs appeared only with the Greeks of the classical period.
An interesting early case is that of what we now call the Euclidean algorithm. In its basic form (namely, as an algorithm for computing the greatest common divisor) it appears as Proposition 2 of Book VII in "Elements", together with a proof of correctness. However, in the form that is often used in number theory (namely, as an algorithm for finding integer solutions to an equation formula_78,
or, what is the same, for finding the quantities whose existence is assured by the Chinese remainder theorem) it first appears in the works of Āryabhaṭa (5th–6th century CE) as an algorithm called
"kuṭṭaka" ("pulveriser"), without a proof of correctness.
Acronym
By 1943, the term "acronym" had been used in English to recognize abbreviations (and contractions of phrases) that were pronounced as words. (It was formed from the Greek words , ', "topmost, extreme" and , ', "name.") For example, the army offense of being "absent without official leave" was abbreviated to "A.W.O.L." in reports, but when pronounced as a word ("awol"), it became an acronym. While initial letters are commonly used to form an acronym, the original definition was "a word made from the initial letters or syllables of other words", for example UNIVAC from UNIVersal Automatic Computer.