What is the meaning of Ack?

ISO 639-3 language code for Aka-Kora.

The letter A as used in signalling and other types of communications.

acknowledgment signal

Alternative form of ACK.

acknowledged

Expressing distaste, alarm, or trepidation.

act

to act

alas, oh (exclamation of sorrow, awe, etc. – being moved by emotion)

an electric accumulator.

Source: wiktionary.org