Probably a short form of SILVANUS
. This is the name of a companion of Saint Paul
in the New Testament
. Paul refers to him as Silvanus
in his epistles, though it is possible that Silas
was in fact a Greek form of the Hebrew name SAUL
As an English name it was not used until after the Protestant Reformation. It was utilized by George Eliot for the title character in her novel 'Silas Marner' (1861).