Source : Webster's Revised Unabridged Dictionary (1913)

Inadequate \In*ad"e*quate\, a. [Pref. in- not + adequate: cf. F.
   inad['e]quat.]
   Not adequate; unequal to the purpose; insufficient;
   deficient; as, inadequate resources, power, conceptions,
   representations, etc. --Dryden. -- {In*ad"e*quate*ly}, adv.
   -- {In*ad"e*quate*ness}, n.

Source : WordNet®

inadequately
     adv : in an inadequate manner or to an inadequate degree; "the
           temporary camps were inadequately equipped" [ant: {adequately}]