Idiosyncrasy/ˌɪdiəˈsɪŋkrəsi/ Definition 1 of 2Pro Tip 1/3Personality Trait Refers to unique behaviors that define a person's character. His idiosyncrasy of always wearing mismatched socks made him stand out. Pro Tip 2/3Charming Quirk Often seen as an endearing quality that makes a person interesting. Her habit of humming while she cooks is one of her charming idiosyncrasies. Pro Tip 3/3Cultural Significance Can denote behaviors specific to cultural or family traditions. The idiosyncrasy of serving dessert before dinner is a family tradition.