morpheme

noun

1. The smallest linguistic unit within a word that can carry a meaning. It may be a letter, a syllable, or otherwise.

   “Just as a regiment is ultimately made up of soldiers, so the sentence is of morphemes—they are its ultimate constituents.”

   “There is therefore a natural tendency in both American and European structural linguistics to insist that the word should be syntactically decomposed. For writers such as Hockett (1958), or for that matter the early Chomsky (1957), the indivisible unit of grammar was the morpheme, and the relationship of morpheme to morpheme within the word […] was to be handled no differently from that of word to word in any larger structure.”