Sylvester, St.

Sylvester, St., the name of three Popes: S. I., Pope from 314 to 335; S. II., Pope from 999 to 1003, alleged, from his recondite knowledge as an alchemist, to have been in league with the devil; and S. III., Anti-Pope from 1041 to 1046.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)