1.nounSomeone possessing extraordinary intelligence or skill; especially somebody who has demonstrated this by a creative or original work in science, music, art etc.
"I think that would qualify as not smart, but genius... and a very stable genius at that!"
2.nounExtraordinary mental capacity.
3.nounInspiration, a mental leap, an extraordinary creative process.
"a work of genius."
4.nounThe tutelary deity or spirit of a place or person.