What is the term for the involuntary relinquishment of a known right?

The term that accurately describes the involuntary relinquishment of a known right is known as "estoppel." This legal concept prevents a party from arguing something contrary to a claim made or implied by their previous actions or statements. In essence, if someone has asserted a position and another party has relied on that assertion, the first party cannot later change their position, as doing so would unfairly disadvantage the second party.

In the context of insurance and legal compliance, estoppel ensures that all parties operate on an agreed-upon understanding, protecting rights and expectations based on prior conduct, thus maintaining fairness and integrity in contractual relationships. This is particularly relevant when parties have acted in reliance on a situation or position that has due consequences in dealings.

Other terms like "waiver" refer more to a voluntary relinquishment of a known right, typically involving active consent or choice rather than the involuntariness implied in estoppel. Liability pertains to legal responsibility for one's actions, and negligence refers to the failure to exercise appropriate care, leading to damage or injury, but these concepts do not express the relinquishment of rights in the same manner as estoppel.