Ack-ack

Origin

From ack ("A") + ack ("A"), RAF WWI signalese for AA ("anti-aircraft"). (In modern signalese it would be called alpha-alpha.)

Full definition of ack-ack

Noun

1. Antiaircraft artillery.The army fired upon us with ack-ack.Ack-acks were set up in the square.
2. (uncountable) Antiaircraft fireThe bomber flew through heavy ack-ack.

Adjective

1. Of or relating to antiaircraft warfare.

Synonyms

• (anti-aircraft gun) AAA, AA