morpheme . ( Of the Gr. µ?)(do f?, form, and -ma ). 1. m. Ling. Minimum meaningful unit of grammatical analysis; e.g. , not, me, you, the book, cant-ar, casa-s, cas - ero. 2. m. Ling. Analyzable minimum unit possessing only grammatical meaning; e.g. , no, I, you, the book, cant- ar, House - s, cas - ero. morpheme zero. 1. m. Ling. Which presents only theoretically; e.g. singular man is marked with a m orfema zero number with the plural men, with a morpheme -s.