hypertonia vs tonicity

hypertonia and tonicity both are nouns.

Word	Noun	Adjective	Verb	Adverb
hypertonia	Yes	No	No	No
tonicity	Yes	No	No	No

As nouns, tonicity is a hypernym of hypertonia; that is, tonicity is a word with a broader meaning than hypertonia:

hypertonia: (of muscular tissue) the state of being hypertonic
tonicity: the elastic tension of living muscles, arteries, etc. that facilitate response to stimuli

Other hypernyms of hypertonia include tone, tonus.

hypertonia (noun)	tonicity (noun)
(of muscular tissue) the state of being hypertonic	the elastic tension of living muscles, arteries, etc. that facilitate response to stimuli