abnormality vs mental defectiveness

abnormality and mental defectiveness both are nouns.

Word	Noun	Adjective	Verb	Adverb
abnormality	Yes	No	No	No
mental defectiveness	Yes	No	No	No

As nouns, abnormality and mental defectiveness are synonyms defined as:

abnormality and mental defectiveness: retardation sufficient to fall outside the normal range of intelligence

abnormality (noun)	mental defectiveness (noun)
behavior that breaches the rule or etiquette or custom or morality	retardation sufficient to fall outside the normal range of intelligence
marked strangeness as a consequence of being abnormal
retardation sufficient to fall outside the normal range of intelligence
an abnormal physical condition resulting from defective genes or developmental deficiencies