Breadcrumb Home > Thesaurus > E Synonyms of er Find synonyms for: Noun 1. erbium, Er, atomic number 68, metallic element, metal usage: a trivalent metallic element of the rare earth group; occurs with yttrium 2. emergency room, ER, hospital room usage: a room in a hospital or clinic staffed and equipped to provide emergency care to persons requiring immediate medical treatment WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of er (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: avatar Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language