Ack or ACK may refer to:
Ackworth is a village and civil parish in the metropolitan borough of Wakefield, West Yorkshire, England, situated between Pontefract, Barnsley and Doncaster on the small River Went.
In computability theory, the Ackermann function, named after Wilhelm Ackermann, is one of the simplest and earliest-discovered examples of a total computable function that is not primitive recursive.
Bernard Stanley "Acker" Bilk, MBE (28 January 1929 – 2 November 2014) was an English clarinettist and vocalist known for his appearance – goatee, bowler hat and striped waistcoat – and breathy, vibrato-rich, lower-register clarinet style.
The ackee, also known as achee, ackee apple or ayee (Blighia sapida) is a member of the Sapindaceae (soapberry family), as are the lychee and the longan.
Ackworth School is an independent school located in the village of High Ackworth, near Pontefract, West Yorkshire, England.
Ackley is a city in Franklin and Hardin Counties in the U.S. state of Iowa. The population was 1,589 at the 2010 census.
Ackerly Creek is a tributary of South Branch Tunkhannock Creek in Lackawanna County, Pennsylvania, in the United States.
Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.
In data networking and telecommunications, an acknowledgement (or acknowledgment) is a signal passed between communicating processes or computers to signify acknowledgement, or receipt of response, as part of a communications protocol.