Source : Webster's Revised Unabridged Dictionary (1913)

Demosthenic \Dem`os*then"ic\, a. [L. Demosthenicus: cf. F.
   D['e]mosth['e]nique.]
   Pertaining to, or in the style of, Demosthenes, the Grecian
   orator.

Source : WordNet®

Demosthenic
     adj : of or relating to Demosthenes or his oratory