rotary motion ro·ta·ry·motion uncommon noun 1. the act of rotating as if on an axis “the rotation of the dancer kept time with the music” Synonymsrotationrotary motion Related words Word family rotate Broader terms motion Narrower terms circumvolutionfeathergyrationpivotpronationspinspiralsupination WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.