ACK in English dictionary ack Meanings and definitions of "ACK" (signalese) A in RAF phonetic alphabet (data communications) acknowledgment signal (radio communications) acknowledged Expressing distaste, alarm, or trepidation. interjection (radio communications) acknowledged interjection Expressing distaste, alarm, or trepidation. noun (military, now historical) The letter A as used in signalling and other types of communications. noun (data communications) acknowledgment signal more Grammar and declension of ACK ack ( plural acks) ack (plural acks) more ACK Meanings and definitions of "ACK" noun (Internet) An acknowledgement either of a packet or a message received from a network. more Grammar and declension of ACK ACK (plural ACKs) more Ack Sample sentences with "ACK" Declension Stem Try again Available translations Arabic Chinese Dutch French German Hungarian Interglossa Italian Japanese Polish Russian Santali Slovenian Spanish Tamil Vietnamese Authors