The meaning of LUNATIC is someone affected with a severely disordered state of mind. How to use lunatic in a sentence.

Lunatic is a term referring to a person who is seen as mentally ill [1], dangerous, foolish, [2][3] or crazy [4] —conditions once attributed to "lunacy". The word derives from lunaticus meaning "of the moon" …

A lunatic is someone who is either clinically insane or just acting really crazy. Someone driving too fast and zigging in and out of traffic is driving like a lunatic.

LUNATIC definition: 1. someone who behaves in a silly or dangerous way: 2. a word for a person who has a mental…. Learn more.

1. Affected by lunacy; mentally deranged. 2. Of or for people who are mentally deranged. 3. Wildly or giddily foolish: a lunatic decision.

If you describe someone as a lunatic, you think they behave in a dangerous, stupid, or annoying way.

lunatic, adj. & n. meanings, etymology, pronunciation and more in the Oxford English Dictionary

Definition of lunatic noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Feb 12, 2026 · Adjective lunatic (comparative more lunatic, superlative most lunatic) Crazed, mad, insane, demented. (literary, rare) Relating to the Moon; lunar.

"Lunatic" is an informal term referring to people who are considered mentally ill, dangerous, foolish or unpredictable; conditions once called lunacy. The term may be considered insulting in serious …