DemosthenesPronunciation: /dɪˈmɒsθəniːz/Definition of Demosthenes (384–322 bc), Athenian orator and statesman. He is best known for his political speeches on the need to resist the aggressive tendencies of Philip II of Macedon (the Philippics). Derivatives DemosthenicPronunciation: /dɛmɒsˈθɛnɪk/ adjective Demosthenes in other Oxford dictionaries Definition of Demosthenes in the US English dictionary