1. The task, together with the purpose, that clearly indicates the action to be taken and the reason therefore. 2. In common usage, especially when applied to lower military units, a duty assigned to an individual or unit; a task. 3. The dispatching of one or more aircraft to accomplish one particular task.
MISSION
Meaning of MISSION in English
DOD English dictionary of military terms. Английский словарь военных терминов DOD. 2012