RETARDATION

[noun] [U] [formal]Retardation is the process of making something happen or develop more slowly than it should.The drugs taken by the women while they were pregnant caused growth retardation in their children.USAGE: Retarded and retardation are no longer used as specialized terms in the care of people with slow mental development, and some people find them offensive.(formal) Mental retardation is slow mental development.The principles of care for people with mental retardation have undergone radical changes over the past 20 years.