If someone is subnormal, they have less ability or intelligence than a normal person of their age. educationally subnormal children. The subnormal are people who are subnormal. She attended a school for the educationally subnormal. less or lower than normal
That part of the axis of a curved line which is intercepted between the ordinate and the normal
below normal or average; "after the floods the harvests were subnormal"; "subnormal intelligence"