(~s)
1.
Rotation is circular movement. A ~ is the movement of something through one complete circle.
...the daily ~ of the earth upon its axis.
N-VAR
2.
The ~ of a group of things or people is the fact of them taking turns to do a particular job or serve a particular purpose. If people do something in ~, they take turns to do it.
Once a month we met for the whole day, and in ~ each one led the group.
N-UNCOUNT: oft in N