Source : Webster's Revised Unabridged Dictionary (1913)

Zest \Zest\, v. t. [imp. & p. p. {Zested}; p. pr. & vb. n.
   {Zesting}.]
   1. To cut into thin slips, as the peel of an orange, lemon,
      etc.; to squeeze, as peel, over the surface of anything.

   2. To give a relish or flavor to; to heighten the taste or
      relish of; as, to zest wine. --Gibber.

Zest \Zest\, n. [F. zeste, probably fr. L. schistos split,
   cleft, divided, Gr. ?, from ? to split, cleave. Cf.
   {Schism}.]
   1. A piece of orange or lemon peel, or the aromatic oil which
      may be squeezed from such peel, used to give flavor to
      liquor, etc.

   2. Hence, something that gives or enhances a pleasant taste,
      or the taste itself; an appetizer; also, keen enjoyment;
      relish; gusto.

            Almighty Vanity! to thee they owe Their zest of
            pleasure, and their balm of woe.      --Young.

            Liberality of disposition and conduct gives the
            highest zest and relish to social intercourse.
                                                  --Gogan.

   3. The woody, thick skin inclosing the kernel of a walnut.
      [Obs.]

Source : WordNet®

zest
     n 1: vigorous and enthusiastic enjoyment [syn: {gusto}, {relish},
           {zestfulness}]
     2: a tart spiciness [syn: {nip}, {piquance}, {piquancy}, {tang},
         {tanginess}]

zest
     v : add herbs or spices to [syn: {spice}, {spice up}]

Source : Free On-Line Dictionary of Computing

ZEST
     
        An {object-oriented} extension of {Z}.
     
        ["Object Orientation in Z", S. Stepney et al eds, Springer
        1992].