Rotary motion is motion in a circle. The starting point for many mechanisms.

Measurement:
Rotary motion is measured in either angular velocity, the number of degrees turned in a given time, or in revolutions per minute (rpm).
The direction of turn, either clockwise or anti-clockwise is also part of the measurement of rotary motion.

The strength of rotary motion is known as the torque, the turning force. Torque is measured in Newton Metres defined as the force of one newton acting at a perpendicular distance of one metre from the axis of rotation.