American Heritage® Dictionary of the English Language, Fourth
Edition - n. A speech sound, such as a glide or liquid, produced
by narrowing but not blocking the vocal tract, as by placing an
articulator, such as the tongue, near another part of the vocal
tract. Century Dictionary and Cyclopedia - Approaching in
character; approximating. “Remember the sonority hierarchy:
fricative approximant vowel.” “Depending on the variety of
Spanish, this can be a lateral, an approximant, a fricative or
an affricate or even a plosive.” “I would expect a French or
German speaker to use a uvular R at the beginning of the family
name, a dental L, N and D, and a clear L in the first name,
where English speakers would have an approximant R, alveolar L,
N, and D, and a dark L.” “In my sole view, if the letter phi is
already being used to write a bilabial fricative (which sounds
like "f"), then it's conceivable to me that initial /w-/ in
Etruscan (written as "v") could have evolved into a bilabial
approximant or voiced fricative