What is "defeasibility"

n. State or instance of being defeasible.

Defeasibility is the property of something – such as a contract, a proposition or an understanding – that can be annulled, invalidated, or similarly "defeated". In law, it refers to the possibility of a contract or other legal agreement being terminated by circumstances that arise later, or of legal reasoning being overturned. In philosophy – especially in epistemology, ethics, or the philosophy of law – it refers to the possibility of a particular principle, rule or understanding being overridden in appropriate circumstances.