rotary joint vs rotatory joint

rotary joint and rotatory joint both are nouns.

Word	Noun	Adjective	Verb	Adverb
rotary joint	Yes	No	No	No
rotatory joint	Yes	No	No	No

As nouns, rotary joint and rotatory joint are synonyms defined as:

rotary joint and rotatory joint: a freely moving joint in which movement is limited to rotation

Other synonyms of rotary joint include articulatio trochoidea, pivot joint.

rotary joint (noun)	rotatory joint (noun)
a freely moving joint in which movement is limited to rotation	a freely moving joint in which movement is limited to rotation