A morphological test for nouns in English and many other languages is whether they can bear plural morphemes. Morphological similarity among members of a given word class can be illustrated by the many adverbs in English that are derived by attaching the suffix – ly, that is, a functional morpheme, to an adjective ( quick, quick-ly). Some examples for both criteria follow: The fact that in English, nouns can be preceded by a determiner such as an article (e.g., a book, the apple) illustrates syntactic distribution. By “morphological similarity,” reference is made to functional morphemes that are part of words belonging to the same word class. The term “part of speech” is a traditional one that has been in use since grammars of Classical Greek (e.g., Dionysius Thrax) and Latin were compiled for all practical purposes, it is synonymous with the term “word class.” The term refers to a system of word classes, whereby class membership depends on similar syntactic distribution and morphological similarity (as well as, in a limited fashion, on similarity in meaning-a point to which we shall return).

What part of speech is the word is