deficient vs inadequacy

deficient

• 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). 

inadequacy

• The state of being inadequate. 

• A lack of competence or ability. 

• A shortage of required material.