ErThe symbol for erbium.ERabbr. emergency roomer (ûr)interj. Used to express hesitation or uncertainty.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.er (?; ??) interj (Phonetics & Phonology) a sound made when hesitating in speecher the internet domain name for (Computer Science) Eritrea Er the chemical symbol for (Elements & Compounds) erbium ER abbreviation for 1. (Medicine) (in the US) Emergency Room (in hospitals) 2. Elizabeth Regina 3. (Historical Terms) Eduardus Rex [Latin: Queen Elizabeth]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014er (?, ?r) interj. (used to express or represent a pause, hesitation, uncertainty, etc.) ER 1. efficiency report. 2. emergency room. Er Chem. Symbol. erbium. -er1 , a noun-forming suffix, added to nouns to form words designating persons from the object of their occupation or labor (hatter; moonshiner; roofer), or from their place of origin or abode (Icelander; southerner), or designating persons or things from some special characteristic or circumstance (double-decker; fourth-grader; tanker; teenager). When added to verbs, -er1 forms nouns denoting a person, animal or thing that performs or is used in performing the action of the verb ( baker; eye-opener; fertilizer; pointer; teacher). Compare -ier 1, -yer.[Middle English -er(e), representing Old English -ere agentive suffix (c. Old High German -?ri, Gothic -areis