The Collaborative International Dictionary of English v.0.48:

Extimulate \Ex*tim"u*late\, v. t. [L. extimulatus, exstimulatus,
   p. p. of extimulare, exstimulare, to goad. See Stimulate.]
   To stimulate. [Obs.] --Sir T. Browne.
   [1913 Webster]