phoneme, in linguistics, smallest unit of speech distinguishing one word (or word element) from another, as the element p in “tap,” which separates that word from “tab,” “tag,” and “tan.” A phoneme may have more than one variant, called an allophone (q.v.), which functions as a single sound; for example, the p's of “
this, feather, then. /ng/ ng, n.sing, monkey, sink. /sh/ sh, ss, ch, ti, ci.special. /ch/ ch, tch.chip, match. /zh/ ge, s.