Which term refers to the intentional and voluntary surrender of a known right?

The term that refers to the intentional and voluntary surrender of a known right is "waiver." A waiver requires that a person consciously chooses to relinquish a legal right, such as the right to sue or the right to a claim. This act is typically done with full knowledge of the implications of giving up that right, reinforcing the intentional nature of the waiver.

In many legal contexts, waivers are utilized in contracts or legal agreements where one party agrees to forego certain rights or claims in exchange for specific benefits or considerations. This concept is crucial in understanding how rights can be legally given up and the balance between legal obligations and individual choices.

In contrast, the other terms listed don't fit the definition of intentional surrender of a known right in the same precise way. Abandonment typically refers to the relinquishment of a right or property without the intention of transferring it to another party. Concession involves yielding to some point or demand made by another party, which doesn't necessarily mean surrendering a known right. Estoppel is a legal principle that prevents someone from arguing something contrary to a claim made or implied by their previous actions or statements, rather than the voluntary surrender of a right itself.