The Collaborative International Dictionary of English v.0.48:

Anticlastic \An`ti*clas"tic\ ([a^]n`t[i^]*kl[a^]s"t[i^]k), a.
   [Pref. anti- = Gr. kla^n to break.]
   Having opposite curvatures, that is, curved longitudinally in
   one direction and transversely in the opposite direction, as
   the surface of a saddle.
   [1913 Webster]