metastable vs metastability

metastable is not a noun while metastability is a noun.

Word	Noun	Adjective	Verb	Adverb
metastable	No	Yes	No	No
metastability	Yes	No	No	No

metastable (noun)	metastability (noun)
	the quality of a physical system that persists in its existing equilibrium when undisturbed (or only slightly disturbed) but able to pass to a more stable equilibrium when sufficiently disturbed

metastable (adjective)	metastability (adjective)
(of physical systems) continuing in its present state of equilibrium unless sufficiently disturbed to pass to a more stable state of equilibrium