rotation

Etymology

Borrowed from Latin rotatiō. By surface analysis, rotate + -ion.

noun

1. (chiefly uncountable) The act of turning around a centre or an axis.
   An extreme version of vorticity is a vortex. The vortex is a spinning, cyclonic mass of fluid, which can be observed in the rotation of water going down a drain, as well as in smoke rings, tornados and hurricanes. 2013-03, Frank Fish, George Lauder, “Not Just Going with the Flow”, in American Scientist, volume 101, number 2, archived from the original on 2013-05-01, page 114
   The earth's rotation about its axis is responsible for its being slightly oblate rather than a sphere.
2. A single complete cycle around a centre or an axis.
   Earth's moon completes a rotation every twenty-seven days or so.
3. A regular variation in a sequence, such as to even-out wear, or people taking turns in a task; a duty roster.
   Applying crop rotation to a field avoids depleting soil nutrients the way repeated use of a single crop might do.
   In rotation, each member of the group would be responsible for the beacon fire.
   The medical resident finished a two-week rotation in pediatrics and began one in orthopaedics.
4. (mathematics, geometry) An operation on a metric space that is a continuous isometry and fixes at least one point.
   The function mapping (x,y) to (−y,x) is a rotation.
5. (baseball) The set of starting pitchers of a team.
6. (aviation) The step during takeoff when the pilot commands the vehicle to lift the nose wheel off the ground during the takeoff roll. (see also: V2)
7. Repeated play on a radio station, etc.
   The new single enjoyed heavy rotation on MTV.