Definition of: idea

(ī·dē′ə) noun
1. Any notion or thought: the idea of a horse or of happiness.
2. The result of thinking; a definitely formulated thought; an opinion: a clear idea of social justice.
3. A plan or project: to have an idea of going into business.
4. A concept; a mental representation of something perceived through the senses.
5. A vague thought or fancy; supposition: I had no idea you'd come.
6. Colloq. Meaning; aim: What's the idea?
7. In Platonic philosophy, the archetype or external pattern of which all existing things are imperfect representations.
8. Obs. The embodiment of a conception, belief, or view. [<L <Gk. <idein see] Synonyms: apprehension, archetype, belief, conceit, concept, conception, design, fancy, fantasy, ideal, image, imagination, impression, judgment, model, notion, opinion, pattern, plan, purpose, sentiment, supposition, theory, thought. Idea is in Greek a form or an image. The sense implied by early Platonic philosophy has nearly disappeared and has been largely appropriated by ideal, but something of the original meaning still appears when in theological or philosophical language we speak of the ideas of God. The present popular use of idea makes it signify any product of mental apprehension or activity, considered as an object of knowledge or thought; this coincides with the primitive sense at but a single point
—that an idea is mental as opposed to anything substantial or physical; thus, almost any mental product, as a belief, conception, design, opinion, etc., may now be called an idea. Compare FANCY, IDEAL, IMAGF. THOUGHT¹. Antonyms: actuality, fact, reality, substance.