A person who is deficient.
Insufficient or inadequate in amount.
Lacking something essential; often construed with in.
Of a number n, Having the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n).
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.
denormal
Less than normal.