imperfectness vs defect

imperfectness and defect both are nouns.

Word	Noun	Adjective	Verb	Adverb
imperfectness	Yes	No	No	No
defect	Yes	No	Yes	No

As nouns, defect is a hyponym of imperfectness; that is, defect is a word with a more specific, narrower meaning than imperfectness:

Other hyponyms of imperfectness include failing, weakness, flaw, fault, flaw, wart, defectiveness, faultiness, nonoptimality.

imperfectness (noun)	defect (noun)
the state or an instance of being imperfect	a mark or flaw that spoils the appearance of something (especially on a person's body)
	a failing or deficiency
	an imperfection in an object or machine
	an imperfection in a bodily system

imperfectness (verb)	defect (verb)
	desert (a cause, a country or an army), often in order to join the opposing cause, country, or army