The Collaborative International Dictionary of English v.0.48:

Heighten \Height"en\ (h[imac]t"'n), v. t. [Written also
   highten.] [imp. & p. p. Heightened; p. pr. & vb. n.
   Heightening.]
   1. To make high; to raise higher; to elevate.
      [1913 Webster]

   2. To carry forward; to advance; to increase; to augment; to
      aggravate; to intensify; to render more conspicuous; --
      used of things, good or bad; as, to heighten beauty; to
      heighten a flavor or a tint. "To heighten our confusion."
      --Addison.
      [1913 Webster]

            An aspect of mystery which was easily heightened to
            the miraculous.                       --Hawthorne.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "heightened":
   accelerated, aggrandized, aggravated, amplified, annoyed,
   augmented, beefed-up, bloated, boosted, broadened, deepened,
   deliberately provoked, elevated, embittered, enhanced, enlarged,
   exacerbated, exasperated, expanded, extended, heated up, hiked,
   hotted up, increased, inflated, intensified, irritated, jazzed up,
   magnified, multiplied, proliferated, provoked, raised, reinforced,
   soured, spread, stiffened, strengthened, swollen, tightened,
   widened, worse, worsened