Far beyond physical attractiveness, to me at least, beauty is a combination of (not necessarily conventional "good looks") expressive, witty or charming features, add a touch of intelligence, a sense of style, a certain self-confidence (but not necessarily that kind of self-confidence generic self-help books promote), a certain open-mindedness, combined with a care for both attire and personality
What do intelligence, sense of style, wit etc. have in common with beauty? Almost anything since, while these qualities do not necessarily generate or enhance physical beauty, they do add up to the overall qualities which eventually make me perceive a person as both beautiful, but also charming and complex