Mental giftedness could equate to a high IQ, special skill sets or talents, abilities to teach others, habits of grasping knowledge and using it to other benefits

Giftedness is typically thought to result from a combination of genetic factors and environmental influences. Some children may be born with certain abilities or predispositions that contribute to giftedness, but supportive and stimulating environments also play a key role in developing and nurturing these talents. It is believed that both nature and nurture contribute to the development of giftedness in children.

Colleen O'Brien has written:

'Asperger's syndrome or giftedness?'

There is a word Giftedness (which is a noun) meaning having special talent and ability

An IQ of 20 - 49 used to be classed as "Imbecile".