Instant centre of rotation

The instant center of rotation (also known as instantaneous velocity center, instantaneous center, or pole of planar displacement) of a body undergoing planar movement is a point that has zero velocity at a particular instant of time. At this instant, the velocity vectors of the other points in the body generate a circular displacement field around this center of rotation which is identical to what is generated by a pure rotation.

Source: Wikipedia — Instant centre of rotation (CC BY-SA 4.0)