Quartermaster is a military term, the meaning of which depends on the country and service. In land armies, a quartermaster is generally a relatively senior soldier who supervises stores or barracks and distributes supplies and provisions. In many navies, a quartermaster is an officer with particular responsibility for steering and signals. The seaman is a non-commissioned officer (petty officer) rank; in some others, it is not a rank but a role related to navigation.

The term appears to derive from the title of a German royal official, the Quartiermeister. This term meant "master of quarters" (where "quarters" refers to lodging or accommodation). Alternatively, it could have been derived from "master of the quarterdeck" where the helmsman and captain controlled the ship. The term's first use in English was as a naval term, which entered English in the 15th century via the equivalent French and Dutch naval titles quartier-maître and kwartier-meester, respectively. The term began to refer to army officers in English around 1600.