a whip used as an instrument of punishment consisting of nine pieces of knotted line or cord fastened to a handle; -- formerly used to flog offenders on the bare back; -- called also the cat. It was used in the British Navy to maintain discipline on board sailing ships.

When a soldier was ordered to be punished, the most common punishment was the administration of lashes by the drummers of the regiment. The drummer would whip the offender with a Cat o' Nine Tails, a leather whip with nine knotted cords or strands.

A short nine-tailed whip kept by the bosun's mate to flog sailors (and soldiers in the Army).

the Bosuns' Mate kept this nine tailed whip used for flogging.

The Cat O' Nine Tails is a type of multi-tailed whipping device that originated as an implement for severe physical punishment as in the British Royal Navy.