The Collaborative International Dictionary of English v.0.48:

Dissimulate \Dis*sim"u*late\, a. [L. dissimulatus, p. p. of
   dissimulare. See Dissemble.]
   Feigning; simulating; pretending. [Obs.] --Henryson.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dissimulate \dis*sim"u*late\, v. i.
   To dissemble; to feign; to pretend.
   [1913 Webster]