restraint; a bar. Estoppel arises where a person has done some act that the policy of the law will not permit him to deny, or where circumstances are such that the law will not permit a certain argument because it would lead to an unjust result. In the context of contract law, for example, one is estopped from denying existence of a binding contract where one has done something intending that another rely on his conduct, and the result of the reliance is detrimental to that other person.

stop or bar, such that one party makes a statement upon which a second party has every reason to rely, thereby preventing the first party from denying the validity of that statement. For example, the misleading actions of an agent of the insurance company result in the insured being estopped from having to perform according to the provisions of the contract.

a doctrine of law that stops one from later denying facts which that person once acknowledged were true and others accepted on good faith .

Example: Abel signs a certificate acknowledging that he owes $10,000 on a mortgage as of a certain date. Later he contends that he owed only $5,000. Abel is prevented from asserting this new contention under estoppel.