Definition of didymium in English:

Share this entry


Pronunciation: /dīˈdimēəm/


A mixture containing the rare earth elements praseodymium and neodymium, used to color glass for optical filters. It was originally regarded as a single element.
Example sentences
  • In 1879 Paul-Emile Lecoq, gallium's discoverer, announced that there was another element contaminating didymium, which he called samarium.
  • The discovery of praseodymium is credited to the Austrian chemist Carl Auer who found that a previously discovered element, didymium, was actually a mixture of two other new elements.
  • Didymia, and its supposed elemental associate, didymium, then vanished from the chemical pantheon.


Mid 19th century: from Greek didumos 'twin' (because it was closely associated with lanthanum) + -ium (used as a suffix for new metals).

For editors and proofreaders

Syllabification: di·dym·i·um

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.