means A flaw, defect, or shortcoming — the place where something falls short of being flawless.

from From Latin imperfectus, 'unfinished' or 'incomplete,' built from the negating prefix in- ('not') plus perfectus, the past participle of perficere, 'to complete' (per-, 'thoroughly,' and facere, 'to make' — a cousin of words like fact and factory). The English form arrived through Old French in the late Middle Ages. So at its root, an imperfection isn't a failure but a thing simply not-yet-finished.