1. A person who puts forward a legal instrument for consideration or acceptance; esp., one who offers a will for probate. [Cases: Wills 211, 219. C.J.S. Wills §§ 453–456, 468.]
2. A person who puts forward a proposal; one who argues in favor of something (a proponent of gun control).
3. Parliamentary law. A member who speaks in favor of a pending motion. Cf. OPPONENT(3).