As a noun ack is
the letter a as used in signalling and other types of communications.
As an interjection ack is
(radio communications) acknowledged or ack can be expressing distaste, alarm, or trepidation.
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Not English
Wikidiffcom has no English definition. It may be misspelled. ack
Alternative forms
* ack
Noun
(
en noun)
(internet) An acknowledgement either of a packet or a message received from a network.
Antonyms
* NAK