«А morpheme is the smallest indivisible meaningful language unit within the structure of the word». Morphemes are subdivided into roots and affixes. The root-morpheme is the lexical nucleus of a word and a common part of a word-building cluster. Affixes are classified into prefixes, suffixes and infixes. According to their function and meaning affixational morphemes are subdivided into: grammatical affixes, serving to form new grammatical forms of the same word and derivational, building new words. Structurally morphemes fall into free and bound. Semi-free or semi-bound morphemes (semi-affixes) are identical to roots in their form, but have acquired the functional and semantic characteristics of derivational affixes to a certain degree. The positional variants of a morpheme are called allomorphs.
