Source : Webster's Revised Unabridged Dictionary (1913)

Defective \De*fect"ive\, a. [L. defectivus: cf. F. d['e]fectif.
   See {Defect}.]
   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. (Gram.) Lacking some of the usual forms of declension or
      conjugation; as, a defective noun or verb. --
      {De*fect"ive*ly}, adv. -- {De*fect"ive*ness}, n.

Defective \De*fect"ive\, n.
   1. Anything that is defective or lacking in some respect.

   2. (Med.) One who is lacking physically or mentally.

   Note: Under the term defectives are included deaf-mutes, the
         blind, the feeble-minded, the insane, and sometimes,
         esp. in criminology, criminals and paupers.

Source : WordNet®

defective
     adj 1: having a defect; "I returned the appliance because it was
            defective" [syn: {faulty}]
     2: markedly subnormal in structure or function or intelligence
        or behavior; "defective speech"
     3: not working properly; "a bad telephone connection"; "a
        defective appliance" [syn: {bad}]