discontinuous vs discontinuity

discontinuous is not a noun while discontinuity is a noun.

Word	Noun	Adjective	Verb	Adverb
discontinuous	No	Yes	No	No
discontinuity	Yes	No	No	No

discontinuous (noun)	discontinuity (noun)
	lack of connection or continuity

discontinuous (adjective)	discontinuity (adjective)
not continuing without interruption in time or space
of a function or curve; possessing one or more discontinuities