LH:

A term from linguistics. Just as a phoneme is the smallest unit of distinguishable sound, a morpheme is the smallest unit of distinguishable sound with meaning. In English, for example, "t'e" is a sound one can make (the sound of the letter t by itself) by has no meaning. "tu-" has meaning, just by adding the stretch into "oo" at the end. SIngle vowels with meaning, such as "I" and "a" are the smallest morphemes. Words are made up of morphemes which are made up of phonemes.

A