So far in looking at structure class words, we have looked at
Now we’re going to look at the rest of the structure class words, which include
As a review, unlike form class words, which can change their form – and sometimes their meaning – by accepting morphemes (so that chair becomes chairs or run becomes runner), structure class words do not usually accept morphemes.
Also, unlike form class words, which carry most of the semantic meaning of the sentence, the main purpose of structure class words is to carry the structural meaning of the sentence.
A final difference is that form class words are an open set. There are countless nouns, verbs, adjectives, and adverbs, and we add more almost daily. In contrast, the number of prepositions, conjunctions, and pronouns in the language are relatively limited.
(Semantic: the study of meaning; so, here, what a word means literally, as opposed to its structural or grammatical meaning.)