1. A characteristic, habit, or manner that is peculiar or distinctive to an individual; an unusual or eccentric trait.
Usage: Plural form of idiosyncrasy; Often used to describe quirky or unique personal behaviors
2. An unusual or abnormal reaction of an individual to a substance, food, or drug.
Usage: Medical or physiological context

Examples

• Everyone has their own idiosyncrasies—some people organize their books by color, while others arrange them by author.
• Her idiosyncrasies included always wearing mismatched socks and humming while she worked.
• The artist's idiosyncrasies made his paintings instantly recognizable.
• He had several food idiosyncrasies and couldn't eat certain textures.
• Despite their idiosyncrasies, the team worked together effectively.
• The character's idiosyncrasies made him both endearing and frustrating to his friends.