Defective /(?)/

De·fect·ive

Defective

a.
  1. Wanting in something; incomplete; lacking a part; deficient; imperfect; faulty; -- applied either to natural or moral qualities; as, a defective limb; defective timber; a defective copy or account; a defective character; defective rules.
  2. Lacking some of the usual forms of declension or conjugation; as, a defective noun or verb. (Gram.)

Defective

n.
  1. Anything that is defective or lacking in some respect.
  2. One who is lacking physically or mentally. (Med.)