v.
  
/
rɪˈtɑːd/
 delay or hold back in terms of development or progress.
n.
  
/
ˈriːtɑːd/
 
offensive a person who has a mental disability (often used as a general term of abuse).
 
  Derivative
  
    - retardation n.
  - retarder n.
 
   
  Etymology
  C15 (earlier (ME) as retardation): from Fr. retarder, from L. retardare, from re- ‘back’ + tardus ‘slow’.