[de.fec.tive] adj (14c) 1 a: imperfect in form or function: faulty "a ~ pane of glass" b: falling below the norm in structure or in mental or physical function "~ eyesight"
2: lacking one or more of the usual forms of grammatical inflection "must is a ~ verb" -- de.fec.tive.ly adv -- de.fec.tive.ness n
[2]defective n (1881): a person who is subnormal physically or mentally