subnormality vs backwardness

subnormality and backwardness both are nouns.

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

As nouns, subnormality and backwardness are synonyms defined as:

subnormality and backwardness: lack of normal development of intellectual capacities

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

subnormality (noun)	backwardness (noun)
lack of normal development of intellectual capacities	lack of normal development of intellectual capacities
the state of being less than normal (especially with respect to intelligence)