uncollectible vs invalid

uncollectible is not a noun while invalid is a noun.

Word	Noun	Adjective	Verb	Adverb
uncollectible	No	Yes	No	No
invalid	Yes	Yes	Yes	No

uncollectible (noun)	invalid (noun)
	someone who is incapacitated by a chronic illness or injury

uncollectible (adjective)	invalid (adjective)
not capable of being collected	having no cogency or legal force
	no longer valid

uncollectible (verb)	invalid (verb)
	injure permanently
	force to retire, remove from active duty, as of firemen