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).
Someone who lacks confidence or courage, is weak, ineffectual, irresolute and wishy-washy.
To render wimpy.
To behave submissively.