Demosthenic /ˌdɛməsˈθɛnɪk/ adjective1 •Pertaining to or characteristic of Demosthenes, a celebrated Athenian orator (384-322, B.C.), especially famous for his "Phillippics," or orations delivered against the encroachments of Philip, king of Macedon. formsmore Demosthenic · most Demosthenic