The Collaborative International Dictionary of English v.0.48:

Jactation \Jac*ta"tion\ (j[a^]k*t[=a]"sh[u^]n), n. [L. jactatio,
   fr. jactare: af. F. jactation. See Jactancy.]
   A throwing or tossing of the body; a shaking or agitation.
   --Sir. W. Temple.
   [1913 Webster]

WordNet (r) 3.0 (2006):

jactation
    n 1: (pathology) extremely restless tossing and twitching
         usually by a person with a severe illness [syn:
         jactitation, jactation]