Rotation
1. Rotation is the circular movement of an object around an axis of rotation.
2. Rotation is the act or process of turning around a center or an axis.
The speed of rotation is given by the angular frequency (rad/s) or frequency (turns per time), or period (seconds, days, etc.). The time-rate of change of angular frequency is angular acceleration (rad/s²), caused by torque. The ratio of the two (how heavy is it to start, stop, or otherwise change rotation) is given by the moment of inertia.
The angular velocity vector (an axial vector) also describes the direction of the axis of rotation. Similarly the torque is an axial vector.
The physics of the rotation around a fixed axis is mathematically described with the axis–angle representation of rotations. According to the right-hand rule, the direction away from the observer is associated with clockwise rotation and the direction towards the observer with counterclockwise rotation, like a screw.
Lexico Oxford English and Spanish Dictionary, Thesaurus, and Spanish to English Translator. www.lexico.com
Lexico Oxford English and Spanish Dictionary, Thesaurus, and Spanish to English Translator. www.lexico.com
"Rotation", Encyclopedia of Mathematics, EMS Press, 2001 p994