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1550s, from Latin rotationem (nominative rotatio) "a turning about in a circle," noun of action from past participle stem of rotare "turn round, revolve, whirl about, roll," from PIE *roto- (see rotary).
rotation ro·ta·tion (rō-tā'shən)
The act or process of turning around a center or an axis.
Regular and uniform variation in a sequence or series, as in the recurrence of symptoms of a disease.