The Collaborative International Dictionary of English v.0.48:

Kidnap \Kid"nap`\ (k[i^]d"n[a^]p`), v. t. [imp. & p. p.
   Kidnaped (k[i^]d"n[a^]pt`) or Kidnapped; p. pr. & vb. n.
   Kidnaping or Kidnapping.] [Kid a child + Prov. E. nap to
   seize, to grasp. Cf. Knab, Knap, Nab.]
   To take (any one) by force or fear, and against one's will,
   with intent to carry to another place. --Abbott.
   [1913 Webster]

         You may reason or expostulate with the parents, but
         never attempt to kidnap their children, and to make
         proselytes of them.                      --Whately.
   [1913 Webster]

   Note: Originally used only of stealing children, but now
         extended in application to any human being,
         involuntarily abducted. Kidnaper

WordNet (r) 3.0 (2006):

kidnap
    v 1: take away to an undisclosed location against their will and
         usually in order to extract a ransom; "The industrialist's
         son was kidnapped" [syn: kidnap, nobble, abduct,
         snatch]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "kidnap":
   abduce, abduct, capture, carry away, carry off, coax, crimp, decoy,
   entice, hold for ransom, impress, inveigh, lure, make off with,
   return, run away with, seduce, seize, shanghai, skyjack, snatch,
   spirit away, throttle, waylay