(a.) Liable to fail, mistake, or err\; liable to deceive or to be deceived; as, all men are fallible; our opinions and hopes are fallible.

adulterated blemished careless damaged defective deficient errable errant erroneous error-prone faulty found wanting heedless immature impaired imperfect imprecise impure inaccurate inadequate incomplete inexact lacking liable to error makeshift mediocre mixed not perfect off open to error partial patchy short sketchy undeveloped uneven unfinished unperfected unsound unthorough wanting