1
old-fashioned + sometimes offensive
: an unusual slowness of mental development
The child suffered severe mental retardation.
2
formal
: an act of slowing down the development or progress of something
The chemical induced a retardation of cell growth.
Cite this Entry
“Retardation.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/retardation. Accessed 21 Jun. 2026.
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