1 The act of acceding or agreeing, especially when it involves the yielding of part or all of one's own position. 2The act of acceding to, or coming into possession of, an office, right, or title. 3In international law, the formal assent by one county to a treaty between accessory other countries. By doing so, the country becomes a party to the treaty. 4 The acquisition of title to personal property by applying labor that converts it into an entirely different thing (such as turning leather i...