Function word

Words supplying mainly grammatical information, rather than content information

In linguistics, function words are words that have little lexical meaning or have ambiguous meaning and express grammatical relationships among other words within a sentence, or specify the attitude or mood of the speaker. They signal the structural relationships that words have to one another and are the glue that holds sentences together. Thus they form important elements in the structures of sentences.

This keyword could refer to multiple things. Here are some suggestions: