Criteria for word classes

Four types of criteria are employed to set up word classes – syntactic, morphological, morpho-syntactic and semantic. (Semantic criteria have to do with meaning.) We begin with a brief explanation of morphological and morpho-syntactic criteria, which have to do with what is called inflectional morphology. Consider the English examples The tiger is smiling and The tigers are smiling. The contrast between tiger and tigers shows that tigers can be split into tiger and -s. Tiger is the stem and -s is the suffix added to the end of the stem. The stem tiger is a noun and the addition of -s does not affect this property. In contrast, the addition of -ish does affect it; tiger is a noun but tigerish is an adjective. In dictionaries of English, tigerish and tigers are treated differently. Tigerish is listed as a separate lexical item, that is, it might be listed in the same entry as tiger but appear in bold and with a short explanation of its meaning; tigers has no entry at all, since the makers of dictionaries assume that users will know how to convert the singular form of a given noun to a plural form.

Suffixes such as -ish that derive new lexical items are derivational suffixes; suffixes that express grammatical information, such as ‘plural’, are inflectional suffixes. (The term comes from the Latin verb flectere ‘to bend’ and is connected with the idea that, in languages such as Russian with a multitude of inflectional suffixes, nouns, verbs and adjectives have a basic form that is bent by the addition of a suffix.) There is one more property of inflectional suffixes: in the tiger clauses above, tiger combines with is smiling and tigers combines with are smiling. That is, there is linkage between subject noun and verb. Traditionally, a distinction is drawn between agreement and government