n.[U][C]

1. 旋转；【天】自转
   The sun appears to rise and set because of the earth's rotation.

   因为地球在自转，看上去就有了日出和日落。

2. 循环；轮流，交替；（农作物的）轮作
   the rotation of kitchen chores

   轮流做厨房里的杂务

n.

1. the action or process of rotating.
2. US a tour of duty, especially by a medical practitioner in training.