Cat o' nine tails
From wipipedia.org
Traditionally, a Cat o' nine tails (with several variants on punctuation) is a whip consisting of nine knotted cords fastened to a handle.
These days, the term "cat o'nine tails" tends to be more liberally used in BDSM to describe almost any kind of multi-tailed whip, or flogger. These whips are usually made of soft leather and have much less potential for injury than the historical punishment tool that could flay a person's back within a dozen strokes.
The "'cat" is used in flogging. The French version is called a martinet, typically having six straps. In the past, on naval sailing ships, it was known as the "Captain's Daughter".
