an·ti·air·craft I. \| ̷ ̷(ˌ) ̷ ̷|-\adjective Etymology:anti- (I) + aircraft : designed for or concerned with defense against air attack < antiaircraft battery > < antiaircraft shell > < antiaircraft training > II. noun (-s) 1.: an antiaircraft weapon or weapons 2.: the organizations that serve antiaircraft weapons, lights, and pointing devices 3.: the flight and burst of antiaircraft shells