n (context|computing) Playful solving of technical work that requires deep understanding, especially of a computer system.
n (context|computing) Unauthorized attempts to bypass the security mechanisms of an information system or network. See also cracker.
n (pathology) A dry coughing; the emission of a succession of short coughs.
n (sports|chiefly|American football|soccer|rugby) A kick in the shins.
n (context|massage) The act of striking the muscles with the side of the hand.
n (UK|countable) A riding or journey on horseback. (Plural hackings.)
n (obsolete) The operation of working over the faces of rough or worn grindstones with a hack-hammer.
n (obsolete|masonry) The separation of a course of stones into two smaller courses, when there are not enough large stones to form a single course.
n (obsolete|gem-cutting) The cuts and grooves made in the metal laps by holding the cutting edge of a steel blade against them while in motion, for the purpose of providing receptacles or pockets for the powders using in cutting and polishing gems.
n (obsolete|brick-making) The piling of bricks for drying.