n.1. a. The act or process of turning around a center or an axis: the axial rotation of the earth.
b. A single complete cycle of such motion.
2. Mathematics A transformation of a coordinate system in which the new axes have a specified angular displacement from their original position while the origin remains fixed.
3. Regular and uniform variation in a sequence or series: a rotation of personnel; crop rotation.
4. Baseball a. The sequence in which the starting pitchers on a team pitch in games.
b. The pitchers used in such a sequence: a team with an excellent rotation.