rotator
/rəʊˈteɪtə(r)/noun
1- a thing which rotates or which causes something to rotate（自身旋转或使别的物体旋转的）旋转体, 转动体, 旋转器。
1.1
- Anatomy a muscle whose contraction causes or assists in the rotation of a part of the body【剖】回旋肌。