Meaning

noun an officer in command of a military unit

noun someone in an official position of authority who can command or control others

noun a commissioned naval officer who ranks above a lieutenant commander and below a captain

originFrom Middle English comaundour, commaunder, comaunder, borrowed from Old French comandeor, cumandeur, from comander. By surface analysis, command + -er. See command.

Etymology from Wiktionary, CC BY-SA 3.0