function word

n. Function words are words that serve a grammatical function inside a sentence. In contrast to content words (e.g., nouns, verbs, and adjectives), which carry meaning and which make up an infinite class, function words do not carry meaning but serve to perform grammatical functions and always make up a finite class in any given language. In English, the class of function words includes prepositions (in, at, on,...), modal and auxiliary verbs (can, may, have), conjunctions (and, or,...), pronouns (I, you, she,...), determiners (the, a,…).The grammatical functions such words perform include providing information on person, number, gender, tense, mood, aspect, and so forth.

- EMF