An addition or modification of a will is known as a what?

The term that refers to an addition or modification of a will is known as a codicil. A codicil serves as a supplement to a will, allowing the testator (the person who created the will) to make changes or updates to their existing will without having to rewrite the entire document. It must be executed with the same legal formalities as the original will, typically requiring the testator's signature and witnesses, depending on state laws.

A testament typically refers to a will itself but does not imply modification; it is more about the entire document or the act of giving testamentary disposition. A trust is a separate legal arrangement where one party holds property for the benefit of another, and it is not simply an amendment to a will. An estate encompasses all the assets and liabilities of a deceased person, but it does not pertain to the direct modification of a will. Therefore, a codicil is the specific and correct term that addresses the concept of modifying a will.