Source : Webster's Revised Unabridged Dictionary (1913)

Deficient \De*fi"cient\, a. [L. deficiens, -entis, p. pr. of
   deficere to be wanting. See {Defect}.]
   Wanting, to make up completeness; wanting, as regards a
   requirement; not sufficient; inadequate; defective;
   imperfect; incomplete; lacking; as, deficient parts;
   deficient estate; deficient strength; deficient in judgment.

         The style was indeed deficient in ease and variety.
                                                  --Macaulay.

   {Deficient number}. (Arith.) See under {Abundant}. --
      {De*fi"cient-ly}, adv.