[ree-tahr-dey-shuh n]
See more synonyms for retardation on
  1. the act of retarding or state of being retarded.
  2. something that retards; hindrance.
  3. Usually Offensive. slowness or limitation in intellectual understanding and awareness, emotional development, academic progress, etc.See also mental retardation.
  4. Music. a form of suspension that is resolved upward.
Also re·tard·ment [ri-tahrd-muh nt] /rɪˈtɑrd mənt/.

Origin of retardation

1400–50; late Middle English retardacioun < Latin retardātiōn- (stem of retardātiō), equivalent to retardāt(us) (see retard, -ate1) + -iōn- -ion
Related formsre·tard·a·tive [ri-tahr-duh-tiv] /rɪˈtɑr də tɪv/, re·tard·a·to·ry [ri-tahr-duh-tawr-ee, -tohr-ee] /rɪˈtɑr dəˌtɔr i, -ˌtoʊr i/, adjectivenon·re·tar·da·tion, nounnon·re·tard·a·tive, adjectivenon·re·tard·a·to·ry, adjectivenon·re·tard·ment, noun

Usage note Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for retardation


less commonly retardment (rɪˈtɑːdmənt)

  1. the act of retarding or the state of being retarded
  2. something that retards; hindrance
  3. the rate of deceleration
  4. psychiatry the slowing down of mental functioning and bodily movement
Derived Formsretardative or retardatory, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for retardation

early 15c., "fact or action of making slower in movement or time," from Latin retardationem (nominative retardatio) "a delaying," noun of action from past participle stem of retardare "to make slow, delay, keep back, hinder," from re- (see re-), + tardare "to slow" (see tardy). Sense of "educational slowness" is from 1907.

Online Etymology Dictionary, © 2010 Douglas Harper

retardation in Medicine


  1. The condition of being relatively slow in mental, emotional, or physical development.
  2. The extent to which something is held back or delayed.
  3. Mental retardation.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.