In linguistics, what is this group of "categories" called?
In the English language for example, there are at least eight fundamental words that are used for asking different things -- who, what, why, where, when, how, whose, and which. Respectively, they refer to [a person, a thing, a reason, a place, a time, a manner/condition, a possession, and a choice] to say the least of how each can be used. What are the nouns inside the square brackets actually called as a group?
I didn't mean the interrogatives, I'm asking about the things they refer to.