deficient

About 6.26 uses per million words.

Meaning

1. adjective Lacking something essential; often construed with in.

   They were deficient in social skills.

2. adjective Insufficient or inadequate in amount.
3. adjective 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.
4. noun A person who is deficient.

Similar words

insufficient inadequate poor lacking substandard scarce inferior scant skimpy shy

Often followed by

in and mice diet or rats as for children

Word family

deficiently deficients