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1. A metallic mixture, once considered an element, composed of neodymium and praseodymium.
2. A mixture of rare-earth elements and their oxides used chiefly in manufacturing and in coloring various forms of glass.
[From Greek didumos, twin, double (from the fact that it was usually found associated with the previously discovered lanthanum ); see dwo- in Indo-European roots.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. (Elements & Compounds) a mixture of the metallic rare earths neodymium and praseodymium, once thought to be an element
2. (Elements & Compounds) a mixture of rare earths and their oxides used in colouring glass
3. (Colours) a mixture of rare earths and their oxides used in colouring glass
[C19: from New Latin, from Greek didumos twin + -ium]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
di•dym•i•um(daɪˈdɪm i əm, dɪ-)
a mixture of neodymium and praseodymium formerly thought to be an element. Symbol: Di
[< Greek dídym(os) twin (see didymous) + New Latin -ium -ium2; so named by Swedish chemist Carl Mosander (1797–1858), who discovered it in 1843, from its close association with lanthanum]
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