The Collaborative International Dictionary of English v.0.48:

Hypochondriac \Hy`po*chon"dri*ac\, a. [Gr. ? affocated in the
   hypochondrium: cf. F. hypocondriaque, formerly spelt
   hypochondriaque.]
   1. Of or pertaining to hypochondria, or the hypochondriac
      regions.
      [1913 Webster]

   2. Affected, characterized, or produced, by hypochondriasis.
      [1913 Webster]

   Hypochondriac region (Anat.), a region on either side of
      the abdomen beneath the cartilages of the false ribs,
      beside the epigastric, and above the lumbar, region.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hypochondriac \Hy`po*chon"dri*ac\, n.
   A person affected with hypochondria.
   [1913 Webster]

         He had become an incurable hypochondriac. --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hypochondriac
    adj 1: suffering from hypochondria [syn: hypochondriac,
           hypochondriacal]
    n 1: a patient with imaginary symptoms and ailments

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "hypochondriac":
   alcoholic, alternating personality, antisocial personality,
   bowed-down, cast down, dashed, dejected, depressed, despairing,
   despondent, desponding, discouraged, disheartened, disordered,
   disordered personality, dispirited, disturbed,
   disturbed personality, double personality, down, downcast,
   downhearted, drooping, droopy, drug user, dual personality,
   emotionally unstable personality, escapist, feeling low, heartless,
   hostile personality, hypochondriacal, hypochondriast, hysteric,
   idiot, imaginary invalid, immature personality, in low spirits,
   in the depths, in the doldrums, in the dumps,
   inadequate personality, inferior personality, languishing, low,
   low-spirited, malade imaginaire, maladjusted personality,
   mentally defective personality, moral insanity,
   multiple personality, neurasthenic, neuropath, neurotic,
   neurotic personality, paranoid personality, perverse personality,
   pessimistic, phobic, pining, psychasthenic, psychoneurotic,
   psychopath, psychopathic personality, psychotic,
   psychotic personality, schizoid, schizoid personality,
   seclusive personality, sexual psychopath, shut-in personality,
   sociopath, spiritless, split personality, subdued, suicidal,
   valetudinarian, valetudinary, weak personality, weary of life,
   woebegone, world-weary