The Collaborative International Dictionary of English v.0.48:

Enhance \En*hance"\, v. i.
   To be raised up; to grow larger; as, a debt enhances rapidly
   by compound interest.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Enhance \En*hance"\, v. t. [imp. & p. p. Enhanced; p. pr. &
   vb. n. Enhancing.] [Norm. F. enhauncer, enhaucer, OF.
   enhaleier, enhaucier; pref. en- (L. in) + haucier to lift,
   raise up, from an assumed L. altiare, fr. L. altus high; cf.
   Pr. enansar, enanzar, to advance, exalt, and E. advance. See
   Altitude, and cf. Hawser.]
   1. To raise or lift up; to exalt. [Obs.] --Wyclif.
      [1913 Webster]

            Who, naught aghast, his mighty hand enhanced.
                                                  --Spenser.
      [1913 Webster]

   2. To advance; to augment; to increase; to heighten; to make
      more costly or attractive; as, to enhance the price of
      commodities; to enhance beauty or kindness; hence, also,
      to render more heinous; to aggravate; as, to enhance
      crime.
      [1913 Webster]

            The reputation of ferocity enhanced the value of
            their services, in making them feared as well as
            hated.                                --Southey.
      [1913 Webster]

WordNet (r) 3.0 (2006):

enhance
    v 1: increase; "This will enhance your enjoyment"; "heighten the
         tension" [syn: enhance, heighten, raise]
    2: make better or more attractive; "This sauce will enhance the
       flavor of the meat"