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. Hanukkah Origins of the Christmas Holiday Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 Krampus: The Christmas Devil Kwanzaa ✖ Related Content Daily Word Quiz: oungurk Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language