Pillory

A pillory is a device or furniture that's designed to restrain the head and wrists. It often consists of two wooden boards with three large holes in the middle. The device can be opened to trap the wrists and neck and hold them in place. It is often used for whipping or other forms of impact play.

A pillory is often mistakenly referred to as stocks, which only restrain the ankles (and sometimes wrists) while sitting down.

Variations

A pillory most commonly restrains the head and the wrists, but others are also made for BDSM that also include ankles or legs. This can also be part of a larger piece of furniture that would also restrain other parts of the body. The head is not always included. Traditionally, a pillory is attached to the ground with a post or posts, but there are also variations in BDSM that have the person carry the pillory as a restraint.

Origins

The device is often associated with medieval times where it was used as public humiliation, often combined with physical punishment (source).