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, while pointers are usually completely rigid. 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. This is particularly noticeable for Kantai Collection's Katori.
See also
The following tags implicate this tag: holding_riding_crop (learn more).