Dissimulation

dissimulation [di-sim-yuh-LAY-shun]

n. The act of disguising one's true feelings or intentions under a feigned appearance.

[Derives from Latin dis- ("negative") + simulātiōn- ("pretending")]

Dissimulation is in the broader lying category of words, but it isn't precisely a synonym for lying ("telling a falsehood intending to deceive"). Lying is more active and direct deception. Dissimulating is more passive, often a cover-up or a misdirection. Someone who dissimulates might not say anything at all which is false, but he may lead you to think he meant something that is not true or not completely true. While dissimulation can be done to intentionally lead someone in the wrong direction, it can also be done simply to not hurt another person's feelings, as in a white lie.

We have a plethora of fun words in the falsehood family. Here are a handful: bamboozle ("to deceive or get the better of (someone) by trickery, flattery"); canard ("a false or baseless, usually derogatory story, report, or rumor"); casuistry ("specious or excessively subtle reasoning intended to rationalize or mislead"); defraud ("to deceive or get the better of (someone) by trickery, flattery"); equivocation ("the use of expressions susceptible of a double signification, with a purpose to mislead"); and hoax ("something intended to deceive or defraud").

In Secrets: A Memoir of Vietnam and the Pentagon Papers, Daniel Ellsberg shows how his boss at the Department of Defense misled as a part of his job:

As (John McNaughton) got into areas where he had to be especially untruthful or elusive, his Pekin, Illinois, accent got broader till he sounded like someone discussing corn at a country fair or standing at the rail of a river boat. … He simply didn’t mind looking and sounding like a hick in the interests of dissimulation.