1. The action of keeping something secret; such as, the fraudulent failure to reveal information which someone knows and is aware that in good faith he or she should tell another person or authority: Such concealment can at least cause for a cancellation of a contract by the misled person or be the basis for a civil lawsuit for fraud.

2. A covering that serves to hide or to shelter something.
3. A condition of being hidden.
4. Keeping out of sight and from being seen, found, observed, or discovered.
5. Etymology: from Latin concelare; from con-, "completely" + celare, "to hide".