Imperfect
Defined in 2 dictionaries — Black's (1910), Anderson (1889)
Black's Law Dictionary
Henry Campbell Black, M.A. · 1910
As used in various legal compound terms, this word means defective or incomplete; wanting in some legal or formal requisite; wanting in legal sanction or effectiveness; as in speaking of imperfect "obligations," "ownership," "rights," "title," "usufruct," or "wav." See those nouns.
A Dictionary of Law
William C. Anderson · 1889
See Duty, 1; Perfect.