An officer who supplies the place of a superior in his absence; a representative of, or substitute for, another in the performance of any duty.
- A commissioned rank in the U.S. Navy or Coast Guard that is above lieutenant junior grade and below lieutenant commander.
- A first lieutenant.
- A second lieutenant.
- One who holds the rank of lieutenant, first lieutenant, or second lieutenant.
- A commissioned officer in the British and Canadian navies ranking just below a lieutenant commander.
- An officer in a police or fire department ranking below a captain.
- One who acts in place of or represents a superior; an assistant or deputy: the organized crime figure and his lieutenants. See Synonyms at assistant.