遲縮劑
Retarder \Re*tard"er\, n. One who, or that which, retards. Retarder \Re*tard"er\ (r[-e]*t[aum]r"d[~e]r), n. 1. (Steam Boiler) Any of various devices, as a helix of flat metal strip, introduced into a boiler tube to increase the heating effect of the fire. 2. (Photog.) A substance, as potassium bromide, added to a developer to retard its action.