riding crop
A short, semi-rigid whip without a lash. Normally used for horse riding, but nowadays more often associated with BDSM.
Riding crops are often confused with teachers' pointers. A riding crop usually has some flex to it and often widens and flattens into a rectangular shape at its very tip. Pointers are usually thinner, completely rigid and may have an oblong cushion on the end. Even artists sometimes conflate the two.
See also
The following tags implicate this tag: holding_riding_crop (learn more).