The Collaborative International Dictionary of English v.0.48:

paranoid \par"a*noid`\, a.
   1. (Med.) Affected with paranoia; as, a paranoid
      schizophrenic.

   Syn: paranoiac.
        [PJC]

   2. Suffering from delusions of being persecuted by the
      conspiratorial actions of others; having an unwarranted
      suspicion of the motives of others; -- used loosely in a
      negative sense, not as a medical term; as, just because
      you're paranoid doesn't mean they are not out to get you.
      [Colloq.]
      [PJC]

WordNet (r) 3.0 (2006):

paranoid
    adj 1: suffering from paranoia
    n 1: a person afflicted with paranoia [syn: paranoid,
         paranoiac]

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "paranoid":
   brain-damaged, brain-injured, catatoniac, catatonic, certifiable,
   certifiable case, disturbed, manic-depressive, mental, mental case,
   mentally ill, mentally sick, neurotic, paranoiac, psycho,
   psychopath, psychopathic, psychopathic case,
   psychopathic personality, psychotic, schiz, schizo, schizoid,
   schizophrenic, schizy