n. 1 a conception or plan formed by mental effort (have you any ideas?; had the idea of writing a book). 2 a a mental impression or notion; a concept. b a vague belief or fancy (had an idea you were married; had no idea where you were). 3 an intention, purpose, or essential feature (the idea is to make money). 4 an archetype or pattern as distinguished from its realization in individual cases. 5 Philos. a (in Platonism) an eternally existing pattern of which individual things in any class are imperfect copies. b a concept of pure reason which transcends experience. get (or have) ideas colloq. be ambitious, rebellious, etc. have no idea colloq. 1 not know at all. 2 be completely incompetent. not one's idea of colloq. not what one regards as (not my idea of a pleasant evening). put ideas into a person's head suggest ambitions etc. he or she would not otherwise have had. that's an idea colloq. that proposal etc. is worth considering. the very idea! colloq. an exclamation of disapproval or disagreement. idea'd adj. ideaed adj. idealess adj.
[ Gk idea form, pattern f. stem id- see ]