Reverse Dictionary: SELF-POSSESSED

ADJECTIVES
► COLD AS A CUCUMBER perfectly self-possessed; showing no excitement or disturbance of feeling → 1760 obs.
► COOL AS A CUCUMBER alert and aware; self-possessed; calm → World War II Amer. sl.

NOUNS – PERSON
► COOL CARD one who is alert and aware, self-possessed, or calm → World War II Amer. sl.
► COOL CUSTOMER one who is alert and aware, self-possessed, or calm → World War II Amer. sl.
► COOL FISH one who is alert and aware, self-possessed, or calm → World War II Amer. sl.
► COOL HAND a cool, calm, controlled and competent individual; one who is alert and aware, or self-possessed → World War II Amer. sl.