Hesychius the grammarian OF ALEXANDRIA, is of uncertain date, but probably lived about the end of the 4th century. He compiled a Greek Lexicon, which has been of inestimable service to philology and literature. The best edition is that of Alberti and Ruhnken (Leyden, 1746-66, 2 vols.), with additions by Schow (Leipsic, 1792, 8vo); newly edited by Schmidt (Jena, 1857-64, 4 vols. 4to). See Ranke, De Lexici Hesychiani vera origine et genuinaformna Commentatio (Leipzig and Quedlinburg, 1831, 8vo).