（*Pi/stios), i. e. the god of faith and fidelity, occurs as a surname of Zeus, and, according to some, answers to the Latin Fidius or Medius Fidius. (Dionys. A. R. 2.49; Eur. Med. 170.) [L.S]
William Smith. A Dictionary of Greek and Roman biography and mythology. London. John Murray: printed by Spottiswoode and Co., New-Street Square and Parliament Street. In the article on Soranus, we find: "at this present time (1848)" and this date seems to reflect the dates of works cited. 1873 - probably the printing date.