Dictionary entry

Didymium

Webster's Dictionary 1913

Di‐dym″i‐um (?), n.(Chem.) A rare metallic substance usually associated with the metal cerium; — hence its name. It was formerly supposed to be an element, but has since been found to consist of two simpler elementary substances, neodymium and praseodymium. See Neodymium, and Praseodymium.