Bible Dictionaries
Didymium

Webster's Dictionary

(n.) 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.

Bibliography Information
Webster, Noah. Entry for 'Didymium'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​d/didymium.html. 1828.