hypotonia vs hypotonus

hypotonia and hypotonus both are nouns.

Word	Noun	Adjective	Verb	Adverb
hypotonia	Yes	No	No	No
hypotonus	Yes	No	No	No

As nouns, hypotonia and hypotonus are synonyms defined as:

hypotonia and hypotonus: (of muscular tissue) the state of being hypotonic

Other synonyms of hypotonia include hypotonicity.

hypotonia (noun)	hypotonus (noun)
(of muscular tissue) the state of being hypotonic	(of muscular tissue) the state of being hypotonic