rotatory vs rotation

rotatory is not a noun while rotation is a noun.

Word	Noun	Adjective	Verb	Adverb
rotatory	No	Yes	No	No
rotation	Yes	No	No	No

rotatory (noun)	rotation (noun)
	the act of rotating as if on an axis
	a planned recurrent sequence (of crops or personnel etc.)
	a single complete turn (axial or orbital)
	(mathematics) a transformation in which the coordinate axes are rotated by a fixed angle about the origin

rotatory (adjective)	rotation (adjective)
of or relating to or characteristic or causing an axial or orbital turn