The Collaborative International Dictionary of English v.0.48:

Hebetate \Heb"e*tate\, v. t. [imp. & p. p. Hebetated; p. pr. &
   vb. n. Hebetating.] [L. hebetatus, p. p. of hebetare to
   dull. See Hebete.]
   To render obtuse; to dull; to blunt; to stupefy; as, to
   hebetate the intellectual faculties. --Southey
   [1913 Webster]