rotation

noun

• 1the action of rotating about an axis or centre:the moon moves in the same direction as the earth’s rotation [count noun]:several solar rotations
• Mathematics the conceptual operation of turning a system about an axis.
• Mathematicsanother term for curl (sense 3 of the noun).

• 2the passing of a privilege or responsibility to each member of a group in a regularly recurring order:it has become common for senior academics to act as heads of department in rotation
• (also crop rotation) the growing of different crops in succession on a piece of land to avoid exhausting the soil and to control weeds, pests, and diseases: traditional practices such as crop rotation
• Forestry the cycle of growth and felling or cutting of trees: short rotation forestry [count noun]:a rotation of 60-80 years to provide valuable saw timber
• [count noun] US a tour of duty, especially by a medical practitioner in training: she was completing a rotation in trauma surgery