imperfect (adj.)

late 14c., imparfit, "sinful, immoral; not properly formed, not complete, immature; rudimentary, elementary," from Old French imparfait, from Latin imperfectus "unfinished, incomplete, immature," from assimilated form of in- "not, opposite of" (see in- (1)) + perfectus "finished, complete" (see perfect (adj.)). Altered mid-16c. to conform to Latin, along with perfect. Related: Imperfectly.

Others are reading

Definitions of imperfect from WordNet
imperfect (adj.)
not perfect; defective or inadequate;
drainage here is imperfect
imperfect mortals
had only an imperfect understanding of his responsibilities
imperfect (adj.)
wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings;
Synonyms: fallible / frail / weak
imperfect (n.)
a tense of verbs used in describing action that is on-going;
Synonyms: progressive / progressive tense / imperfect tense / continuous tense