Interrogative describes something questioning or that asks a question — like the interrogative tone of a cop grilling a suspect.
It’s likely you first met the word interrogative in elementary school along with its pals — declaratory, exclamatory, and imperative. It can be an adjective or noun, but it always has to do with questions or being questioning. An interrogative sentence is one like "What time is it?" If your voice goes up at the end of a sentence because you're seeking information, your tone is interrogative. If you keep asking question after question, you've being extremely interrogative.