The meaning of CRAZY is not mentally sound : marked by thought or action that lacks reason : insane —not used technically. How to use crazy in a sentence.

Crazy can also mean behaving in a strange way esp. because of stress, as if you are mentally ill:

One who is or appears to be mentally deranged: "To them she is not a brusque crazy, but 'appropriately passionate'" (Mary McGrory).

Dec 14, 2025 · Out of control. When she gets on the motorcycle she goes crazy. Very excited or enthusiastic. quotations He went crazy when he won.

Definition of crazy adjective in Oxford Advanced American Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

If you describe someone or something as crazy, you think they are very foolish or strange.

Caused by or arising from mental derangement; marked by or manifesting insanity: as, a crazy speech; crazy actions. from the GNU version of the Collaborative International Dictionary of English.

to an extreme: We shopped like crazy and bought all our Christmas gifts in one afternoon. Idioms with great speed or recklessness: He drives like crazy once he's out on the highway.

Unsound of mind; mentally unbalanced or deranged; psychopathic; insane. Of or for an insane person. An eccentric or mentally unbalanced person. Used to express approval, pleasure, wonder, etc.: now …

CRAZY definition: mentally deranged; demented; insane. See examples of crazy used in a sentence.