The Etymologicum Genuinum (standard abbreviation E Gen) is the conventional modern title given to a lexical encyclopedia compiled at Constantinople in the mid ninth century. The anonymous compilator drew on the works of numerous earlier lexicographers and scholiasts, both ancient and recent, including Aelius Herodianus, Georgius Choeroboscus, Saint Methodius, Orion of Thebes, Oros of Alexandria and  Theognostus the Grammarian. The Etymologicum Genuinum was possibly a product of the intellectual circle around Photius. It was an important source for the subsequent Byzantine lexicographical tradition, including the Etymologicum Magnum, Etymologicum Gudianum and Etymologicum Symeonis.