In the job search wikis, it means "application acknowledged". Ack is a common exclamation, of general or unwanted surprise ACK as an abbreviation that may refer to: * ACK (computing), a signal used in computing and other fields to indicate acknowledgement, including: * ACK (TCP), a packet message used in the Transmission Control Protocol to acknowledge receipt of a packet. * Acknowledge character, a control character used in ASCII. * ACK (domain transfer), term used in transfer of domains. * Amsterdam Compiler Kit, a fast, lightweight and retargetable compiler suite * Acklington railway station (National Rail: ACK), a rail station in the United Kingdom. * Nantucket Memorial Airport (IATA code: ACK), a Massachusetts airport (referring to Nantucket Memorial Airport).