The basic concepts in the morphological classification of languages are the morpheme and the word. The basic criteria for classification are the nature of the morphemes (lexical and grammatical) combined in a word; the method of their combination, such as pre- or post positioning of grammatical morphemes
(which has a direct relation to syntax) and agglutination, or fusion (related to the field of morphophonemics); and the syntactically related connection between the morpheme and the word (such as isolation, when morpheme = word, or the analytic or synthetic character of word formation and inflection).