an exceptional natural capacity of intellect, especially as shown in creative and original work in science, art, music, etc.: the genius of Mozart. Synonyms: intelligence, ingenuity, wit; brains.
2.
a person having such capacity.
3.
a person having an extraordinarily high intelligence rating on a psychological test, as an IQ above 140. Synonyms: mental giant, master, expert; whiz, brain, brainiac. Antonyms: idiot, imbecile, half-wit, dope, moron; fool, simpleton, dunce, dullard, dolt; numskull, blockhead, nitwit, ninny.
4.
natural ability or capacity; strong inclination: a special genius for leadership. Synonyms: gift, talent, aptitude, faculty, endowment, predilection; penchant, knack, bent, flair, wizardry.
5.
distinctive character or spirit, as of a nation, period, or language.
either of two mutually opposed spirits, one good and the other evil, supposed to attend a person throughout life.
8.
a person who strongly influences for good or ill the character, conduct, or destiny of a person, place, or thing: Rasputin, the evil genius of Russian politics.
late 14c., from L. genius "guardian deity or spirit which watches over each person from birth; spirit, incarnation, wit, talent," from root of gignere "beget, produce" (see kin), from PIE base *gen- "produce." Meaning "person of natural intelligence or talent" first recorded 1640s.