Dissimulation

Dissimulation is a form of deception in which one conceals the truth. It consists of concealing the truth, or in the case of half-truths, concealing parts of the truth, like inconvenient or secret information. Dissimulation differs from simulation, in which one exhibits false information. Dissimulation commonly takes the form of concealing one's ability in order to gain the element of surprise over an opponent.

Francis Bacon has the following to say on the distinction between simulation and dissimulation, "Dissimulation, in the negative; when a man lets fall signs and arguments, that he is not, that he is... Simulation, in the affirmative; when a man industriously and expressly feigns and pretends to be, that he is not." The essay from which this comes can be found here.