Use the noun erotic to describe a sexy, sexy person. What makes that person so sexy? Maybe his or her erotic (here used as an adjective) attitude or looks, meaning "arousing."
The word erotic came into English from French — of course! — and can be traced back to the Greek word erōtikos, from erōs or erōt-, meaning “sexual love.” The adjective erotic is often used to describe a person’s carnal desires, but it can be used to characterize anything that’s sexual in nature or that arouses sexual desires, such as the erotic themes in a racy movie, an erotic dancer in a club, or erotic images in a painting.