Diogenianus the Grammarian (Διογενιανὸς ὁ Γραμματικός) was a Greek lexicographer active during the reign of the emperor Hadrian (117–138 CE) [1][2]. A native of Heraclea in Pontus, he lived in the 2nd century CE under the Roman Empire [1].

His several works, now lost and known only through later references, include the lexicon Περὶ Γλωσσῶν ἢ Λέξεων (Peri Glōssōn ē Lexeōn, "On Dialectal or Uncommon Words"), a primary source for Hesychius of Alexandria [1][2]. Other titles are the Συναγωγὴ Ἐτυμολογιῶν (Synagōgē Etymologiōn, "Collection of Etymologies"), Περὶ Ὀνίθων (Peri Ornithōn, "On Birds"), Περὶ τῆς κατὰ Πόλεις Ἑλλάδος (Peri tēs kata Poleis Hellados, "On the Cities of Greece"), and Ἀστρολογούμενα (Astrologoumena, "Astrological Matters") [1]. He also compiled an anthology of proverbs later epitomized by Zenobius [1][2].

Diogenianus is significant as a key source for later Greek scholarship. His lexicon preserved rare vocabulary for Hesychius, and his proverb collection informed later paremiographers, thereby contributing to the transmission of Greek linguistic and cultural knowledge [1][2].

Sources 1. Encyclopædia Britannica: https://www.britannica.com/biography/Diogenianus 2. Perseus Digital Library, A Dictionary of Greek and Roman biography and mythology: https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0104%3Aentry%3Ddiogenianus-bio-1