dissemble

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To disguise or conceal behind a false appearance. See Synonyms at disguise.
2. v. To make a false show of; feign.
3. v. To disguise or conceal one's real nature, motives, or feelings behind a false appearance.

Century Dictionary and Cyclopedia

1. To make unlike; cause to look different; disguise.
2. To give a false impression about; cause to seem different or non-existent; mask under a false pretense or deceptive manner.
3. To put on the semblance of; simulate; pretend.
4. To assume the appearance of; appear like; imitate.
5. Synonyms Dissemble, Simulate, Dissimulate Disguise, cloak, cover. (See hide.) To dissemble is to pretend that a thing which is is not: as, to dissemble one's real sentiments. To simulate is to pretend that a thing which is not is: as, to simulate friendship. To dissimulate is to hide the reality or truth of something under a diverse or contrary appearance: as, to dissimulate one's poverty by ostentation. To disguise is to put under a false guise, to keep a thing from being recognized by giving it a false appearance: as, I cannot disguise from myself the fact. See dissembler and conceal.
6. To give a false appearance; make a deceptive impression or presentation.
7. To assume a false seeming; conceal the real fact, motives, intention, or sentiments under some pretense; mask the truth about one's self.

Wiktionary

1. v. To disguise or conceal something; to feign.
2. v. To deliberately ignore something; to pretend not to notice.
3. v. To falsely hide one's opinions or feelings.

GNU Webster's 1913

1. v. To hide under a false semblance or seeming; to feign (something) not to be what it really is; to put an untrue appearance upon; to disguise; to mask.
2. v. To put on the semblance of; to make pretense of; to simulate; to feign.
3. v. To conceal the real fact, motives, intention, or sentiments, under some pretense; to assume a false appearance; to act the hypocrite.

WordNet 3.0

1. v. behave unnaturally or affectedly
2. v. make believe with the intent to deceive
3. v. hide under a false appearance