Idea \ahy-DEE-uh\ , noun;
1. Any conception existing in the mind as a result of mental understanding, awareness, or activity
2. A thought, conception, or notion
3. An impression
4. An opinion, view, or belief
5. A plan of action; an intention
Idea dates to the late 14th century as "archetype of a thing in the mind of God" from Latin idea ("idea"). In Platonic philosophy it means "archetype" from Greek idea ("ideal prototype," literally "the look of a thing (as opposed to the reality); form; kind, sort, nature"). Greek idea derives from idein, which comes from Proto-Indo-European *wid-es-ya-, a suffixed form of *weid- ("to see"). *Weid- is also the forebear of vision. The definition "result of thinking" is first attested in the 1640's.