idea, notion

意識(いしき)	Consciousness, as in “I lost consciousness,” but also as in, “She’s environmentally conscious.” or “I hate those socially-conscious rock stars like Bono. Bono should perish.” $$$

観念(かんねん)	To have a concept of something. “Babies have no concept of right and wrong.” “My boyfriend has no concept of hygiene.”

現象(げんしょう)	Phenomenon.