Etymologicum Magnum
Etymologicum Magnum (Ancient Greek: Ἐτυμολογικὸν Μέγα, transl. Ἐtymologikὸn Méga) (standard abbreviation EM, or Etym. M. in older literature) is the traditional title of a Greek lexical encyclopedia compiled at Constantinople by an unknown lexicographer around 1150 AD. It is the largest Byzantine lexicon and draws on many earlier grammatical, lexical and rhetorical works.