Aegyo (Hangeul: 애교) is a Korean expression. The closest English translation of aegyo would be "winsome", defined by the Merriam Webster Dictionary as "generally pleasing and engaging often because of a childlike charm and innocence." Aegyo derives from the Chinese characters "love (ae)" and "beautiful (gyo)."
Aegyo is considered a feminine trait, generally attributed to women who can charm men and elders through a careful balance of sweetness, cuteness, childish mannerism, poutiness, modesty, thoughtfulness, and submissiveness. A woman with aegyo knows to blush at "dirty jokes" rather than guffaw along with her mouth agape. A woman with aegyo knows to let out a modest and appealing squeal and grab tight her date's hand when watching a horror movie.
Aegyo is considered such an essential female trait that there is even a plastic surgery procedure called "aegyo surgery" in which aegyo-sal ((애교살; aegyo-skin) is created on the bottom eyelid to create a sweeter and more innocent appearance.