imperfect vs defective

imperfect is a noun but defective is not a noun.

Word	Noun	Adjective	Verb	Adverb
imperfect	Yes	Yes	No	No
defective	No	Yes	No	No

imperfect (noun)	defective (noun)
a tense of verbs used in describing action that is on-going

imperfect (adjective)	defective (adjective)
not perfect; defective or inadequate	markedly subnormal in structure or function or intelligence or behavior
wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings	having a defect
	not working properly