A sortie (from the French word meaning exit) is a deployment or dispatch of one military unit, be it an aircraft, ship, or troops, from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission. The sortie rate is the number of sorties that a given unit can support in a given time. The term is an evolution of the concept of "sortie" in siege warfare.
In military aviation, a sortie is a combat mission of an individual aircraft, starting when the aircraft takes off. For example, one mission involving six aircraft would tally six sorties.