Cleitarchus of Aegina

Cleitarchus (Κλείταρχος ἐξ Αἰγίνης), originally from Aegina, was a grammarian and lexicographer active in either the 1st or 2nd century BC. He wrote a seven-book treatise titled "Languages" or "On Languages", in which he presented the peculiarities of various Greek dialects and interpreted a multitude of idiomatic words, as well as words derived from specialized professional glossaries.

Cleitarchus and his work are mentioned by Athenaeus, Proclus, Harpocration, and the Byzantine Etymologicum Magnum among others.

All the surviving fragments were collected and published in 1842 in Berlin.