ETYM Latin interrogativus: cf. French interrogatif.
1. Relating to the use of or having the nature of an interrogation; SYN. interrogatory, asking.
2. (Grammar) Relating to verbs in the so-called interrogative mood.

In grammar, a word or sentence expressed as a question. In English, a question normally has inverted word order (verb before subject: “Is that so?”) and may contain an interrogative pronoun (who, whom, which, what) or adverb (where, when, how, why). An interrogative sentence should end with a question mark.
Some sentences may sound interrogative but their meaning is exclamatory (“Was I upset!” “Do you mind!”). Some sentences are interrogative though they appear to be in the form of a statement rather than a question (“These gentlemen are the visitors?”).