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 who is deficient.
Inadequate; insufficiently capable or qualified.
Not the same.
Out of balance.
Erratic, inconsistent.
One who is not an equal.