/ Thesaurus / A Synonyms of atomic number 63 Find synonyms for: Noun1. europium, Eu, atomic number 63, metallic element, metalusage: a bivalent and trivalent metallic element of the rare earth groupWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: lyre Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language