DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Fils \Fils\, n. [F., fr. L. filius. See Filial.]
      Son; -- sometimes used after a French proper name to
      distinguish a son from his father, as, Alexandre Dumas, fils.
      [Webster 1913 Suppl.]