retardation vs stupidity

retardation and stupidity both are nouns.

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

As nouns, stupidity is a hypernym of retardation; that is, stupidity is a word with a broader meaning than retardation:

retardation (noun)	stupidity (noun)
the act of slowing down or falling behind	a stupid mistake
a decrease in rate of change	a poor ability to understand or to profit from experience
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