'Commander in chief' definitions:

Definition of 'commander in chief'

noun

The officer who holds the supreme command; "in the U.S. the president is the commander in chief" [syn: commander in chief, generalissimo]

From: GCIDE

Commander \Com*mand"er\, n. [Cf. F. commandeur. Cf. Commodore, Commender.]
1. A chief; one who has supreme authority; a leader; the chief officer of an army, or of any division of it. [1913 Webster]
A leader and commander to the people. --Is. lv. 4. [1913 Webster]
2. (Navy) An officer who ranks next below a captain, -- ranking with a lieutenant colonel in the army. [1913 Webster]
3. The chief officer of a commandery. [1913 Webster]
4. A heavy beetle or wooden mallet, used in paving, in sail lofts, etc. [1913 Webster]
Commander in chief, the military title of the officer who has supreme command of the land or naval forces or the united forces of a nation or state; a generalissimo. The President is commander in chief of the army and navy of the United States.
Syn: See Chief. [1913 Webster]