concealment

from The Century Dictionary.

• noun The act of concealing, hiding, or keeping secret.
• noun Specifically, in law, the intentional suppression of truth, to the injury or prejudice of another.
• noun The state of being concealed or withdrawn from observation; privacy; retreat.
• noun Shelter from observation; protection from discovery; a place or means of such shelter or protection: as, his only concealment was an arbor of boughs.
• noun In English history, property, as land, the ownership of which was concealed from the commissioners for the dissolution of monasteries, etc., at the time of the Reformation. Also called concealed land.
• noun Secret knowledge; a secret; mystery.
• noun Synonyms and Secrecy, hiding, hiding-place, retreat, disguise.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of concealing; the state of being concealed.
• noun A place of hiding; a secret place; a retreat frem observation.
• noun obsolete A secret; out of the way knowledge.
• noun (Law) Suppression of such facts and circumstances as in justice ought to be made known.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The practice of keeping secrets
• noun The condition of being hidden or concealed
• noun military protection from observation or surveillance

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the condition of being concealed or hidden
• noun the activity of keeping something secret
• noun a covering that serves to conceal or shelter something