Definition of didymium
: a mixture of rare-earth elements made up chiefly of neodymium and praseodymium and used especially for coloring glass for optical filters
Origin and Etymology of didymium
New Latin, from Greek didymos twin, from dyo two — more at two
First Known Use: 1842
Seen and Heard
What made you want to look up didymium? Please tell us where you read or heard it (including the quote, if possible).