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 loser; an unlucky person.
A lottery ticket that does not give a payout.
A failure of any kind.
A device or machine that is useless because it does not work properly or has failed to work, such as a bomb, or explosive projectile.