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, which functions as a single sound; for example, the p’s of “pat,” “spat,” and “tap” differ slightly phonetically, but that difference, determined by context, has no significance in English. In some languages, where the variant sounds of p can change meaning, they are classified as separate phonemes—e.g., in Thai the aspirated p (pronounced with an accompanying puff of air) ... (100 of 208 words)