Definition of "deficient" in English

adjective

1. Lacking something essential; often construed with in.

   • They were deficient in social skills.

2. Insufficient or inadequate in amount.

   • Apothecia lecanoroid; multilocular; each cell containing a single theke; paraphyses deficient.

3. (mathematics) Of a number n, Having the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n)<n.

noun

1. A person who is deficient.