Lacking something essential; often construed with in.
Insufficient or inadequate in amount.
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.
Of one's imagination, etc.: active, productive, prolific.
Of land, etc.: capable of growing abundant crops; productive.
Capable of developing past the egg stage.
Not itself fissile, but able to be converted into a fissile material by irradiation in a reactor.
Capable of reproducing; fecund, fruitful.