Portal:Linguistics/Featured article/October 2008
In morpheme-based morphology, a morpheme is the smallest linguistic unit that has semantic meaning. In spoken language, morphemes are composed of phonemes (the smallest linguistically distinctive units of sound), and in written language morphemes are composed of graphemes (the smallest units of written language).
The concept morpheme differs from the concept word, as many morphemes cannot stand as words on their own. A morpheme is free if it can stand alone, or bound if it is used exclusively alongside a free morpheme. Its actual phonetic representation is the morph, with the morphs representing the same morpheme being grouped as its allomorphs.