noun see: two Date: 1842 a mixture of rare-earth elements made up chiefly of neodymium and praseodymium and used especially for coloring glass for optical filters
DIDYMIUM
Meaning of DIDYMIUM in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012