Someone (usually a woman) who is given the highest accolade of seven dwarfs when being judged on attractiveness. The word derives from the tale of 'Snow White and the Seven Dwarfs' in which Snow White befriends seven dwarfs but is made ill by a poison red apple. Therefore if it is later discovered that a snow white has a major flaw (or weakness), the flaw is termed a red apple (poison red apple or poison apple).
Friend1: "How was Brazil?"
Friend2: "It was full of snow whites."