antiaircraft antiaircraft /ˌæntaɪˈɛrˌkræft/

adjective

1. Designed for defense from a surface position against air attack  ( antiaircraft )
   designed for defense from a surface position against air attack
   

noun

1. Artillery designed to shoot upward at airplanes  ( ack-ack , ack-ack gun , antiaircraft , antiaircraft gun , flack , flak , pom-pom )
   artillery designed to shoot upward at airplanes