(grammar) A word (pronoun, pronominal adjective, or adverb) implying interrogation, or used for asking a question: why, who, when, etc.
A question; an interrogation.
The punctuation mark "?", used at the end of a sentence to indicate a question.
A state of doubt or uncertainty.
An enigmatic, inscrutable, or mysterious person or thing; an enigma, a riddle.
Polygonia interrogationis, a North American nymphalid butterfly with a silver mark on the underside of its hindwing resembling a question mark (sense 1).
(grammar) Asking or denoting a question: as, an interrogative phrase, pronoun, or point.
Pertaining to inquiry; questioning