exclamation mark

Collins Concise English Dictionary © HarperCollins Publishers::

exclamation mark, exclamation point noun

1. the punctuation mark ! used after exclamations and vehement commands
2. this mark used for any other purpose, as to draw attention to an obvious mistake, in road warning signs, (in chess commentaries) beside the notation of a move considered a good one, (in mathematics) as a symbol of the factorial function, or (in logic) occurring with an existential quantifier