Lewis & Short

Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.

Prōtăgŏras, ae, m., = Πρωταγόρας, a celebrated sophist of Abdera, a disciple of Democritus, and an older contemporary of Socrates; he was banished from Athens on a suspicion of atheism, Cic. N. D. 1, 1, 2; 1, 23, 63; id. Ac. 2, 46, 142; id. Brut. 8, 30; 12, 46; Gell. 5, 3, 1 sqq.
Hence, Prōtăgŏrīon, ĭi, n., = Πρωταγόρειον, a dictum or maxim of Protagoras, Gell. 5, 11, 1.