Definition of: captain

(kap′tən, -tin) noun
1. One at the head of or in command of others; a chief; leader; commander.
2. The master or commander of a vessel, regardless of rank.
3. In the U.S. Army, Air Force, or Marine Corps, a commissioned officer ranking next above a first lieutenant and next below a major.
4. In the U.S. Navy and Coast Guard, a commissioned officer ranking next above a commander and next below a rear admiral: equal in rank to a colonel in the Army, Air Force, or Marine Corps. See table under GRADE. See synonyms under CHIEF, MASTER.
—v.t. To be captain over; act as captain to; command; manage; lead. [<OF capitaine <LL capitaneus <L caput head. Doublet of CHIEFTAIN.]
—cap′·tain·cy, cap′tain·ship noun