Definition of "ack-ack" [ack-ack]

• Slang An antiaircraft gun. (noun)
• Slang Antiaircraft fire. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Studying this catalog of wicked devices, Jane observed herself beginning to undergo that change from rookie to hardened field veteran, barely flinching at the sound of ack-ack guns coming from next door, where soldiers practiced shooting at a towed target."
• "Three of us who had talked escape, Mullins, Ford and myself, took off in the pandemonium of ack-ack, bombs, strafing and napalm that hit a nearby building."
• "My favorite was one I painted with a white and blue belly so it was camouflaged to look like clouds and sky to the Nazi ack-ack gunners below."