subnormality vs retardation

subnormality and retardation both are nouns.

Word	Noun	Adjective	Verb	Adverb
subnormality	Yes	No	No	No
retardation	Yes	No	No	No

As nouns, subnormality and retardation are synonyms defined as:

subnormality and retardation: lack of normal development of intellectual capacities

Other synonyms of subnormality include backwardness, mental retardation, slowness.

subnormality (noun)	retardation (noun)
lack of normal development of intellectual capacities	the act of slowing down or falling behind
the state of being less than normal (especially with respect to intelligence)	a decrease in rate of change
	lack of normal development of intellectual capacities
	any agent that retards or delays or hinders
	the extent to which something is delayed or held back