- a mark of punctuation (?) put after a sentence, word, etc. to indicate a direct question, and also used to express doubt, uncertainty, etc.; interrogation mark
- an unknown factor
- A punctuation symbol (?) written at the end of a sentence or phrase to indicate a direct question. Also called interrogation point .
- Something that is unknown, mysterious, or doubtful: Which players will still be on the team next year remains a question mark.