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.
Not fit; not having the correct requirements.
Unsuitable for a particular purpose.
Not fit, not having a good physical demeanor.
To make unfit; to render unsuitable, spoil, disqualify.