Military operations area Regulation
Military operations area. A military operations area (MOA) is airspace established outside Class A airspace to separate or segregate certain nonhazardous military activities from IFR Traffic and to identify for VFR traffic where theses activities are conducted.
Also defined in 1 more source
Airspace established for the purpose of separating certain military training activities from IFR traffic.
Guidance: Pilot's Handbook of Aeronautical Knowledge, p. G-19