To conceal. A withholding of something which one knows and which one, in duty, is bound to reveal (e.g. assets in bankruptcy or divorce proceeding; health condition in insurance application). A "concealment" in law of insurance implies an intention to withhold or secrete information so that the one entitled to be informed will remain in ignorance. Indiana Ins. Co. v. Knoll, 142 Ind.App. 506, 236 N.E.2d 63, 70.
Concealment may be basis of estoppel.
Elements of such estoppel are concealment of material facts with knowledge thereof, ignorance thereof on part of person to whom representations are made, or from whom facts are concealed, intention that such person shall act thereon, and action induced thereby on his part. Rhoads v. Rhoads, 342 Mo. 934, 119 S.W.2d 247, 252; Rosser v. Texas Co., 173 Okl. 309, 48 P.2d 327, 330.
The doctrine of "estoppel by concealment and suppression" applies only where there has been reduction to practice of invention. Bogoslowsky v. Huse, 31 C.C.P.A. (Patents) 1034, 142 F.2d 75, 76

Black's law dictionary. . 1990.