What is the meaning of Subnormal?

Less than normal.

denormal

idiot, stupid.

A person whose abilities are less than normal.

That part of the axis of a curved line which is intercepted between the ordinate and the normal.

Synonym of denormal.

subnormal, less or lower than normal

subnormal

moron, imbecile

subnormal, moronic, stupid

Source: wiktionary.org