1. a doll, blanket, or other thing spontaneously chosen and used by a child to ease the anxiety of separation from his or her first external object, the mother, until the child has established an internal object, or mental representation of her, that provides a sense of security and comfort. [first described by British psychoanalyst Donald Winnicott (1896–1971)]

2. by extension, any person or thing that provides security, emotional well-being, and a symbolic connection with a valued other.