Dictionary.com
Thesaurus.com

retardate

American  
[ri-tahr-deyt] / rɪˈtɑr deɪt /

noun

  1. Older Use: Offensive. a person who has an intellectual disability or is otherwise limited, as educationally or emotionally.


retardate British  
/ rɪˈtɑːdeɪt /

noun

  1. psychol a person who is retarded

"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

Etymology

Origin of retardate

First recorded in 1910–15; probably back formation from retardation