Genius is an exceptional talent or skill, something above and beyond the norm. A genius is someone who possesses this brilliance, like a child prodigy who learned the piano at age 3 and played sold-out concerts by age 5.
Genius comes from the Latin word of the same name, meaning "guardian deity or spirit which watches over each person from birth" or "innate ability." Your genius — your superior talent — at the game of chess could make you a world champion. Your amazing genius would also make you a genius. The word can be used more lightheartedly to describe a natural ability or flair for something. You may have a genius for putting together stylish outfits.