\ˈak \

Definition of ack 

(Entry 1 of 2)

used to express mild alarm or dismay You should see the big wad of lint I just plucked from the trap of my clothes dryer. Ack! Where does all of that come from?— Mary Hunt

Definition of ack (Entry 2 of 2)

acknowledge; acknowledgment

First Known Use of ack

Interjection

2001, in the meaning defined above

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The first known use of ack was in 2001

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