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, is usually black in color, and often widens and flattens into a rectangular shape at its very tip. Pointers usually are completely rigid and smoothly taper to a point. Even artists sometimes conflate the two: teacher characters are regularly depicted holding a riding crop when it makes no sense for them to be doing so besides fetish appeal. This is particularly noticeable for Kantai Collection's Katori.
See also
The following tags implicate this tag: holding_riding_crop (learn more).