The Collaborative International Dictionary of English v.0.48:

Forefather \Fore"fa`ther\ (?; 277), n.
   One who precedes another in the line of genealogy in any
   degree, but usually in a remote degree; an ancestor.
   [1913 Webster]

         Respecting your forefathers, you would have been taught
         to respect yourselves.                   --Burke.
   [1913 Webster]

   Forefathers' Day, the anniversary of the day (December 21)
      on which the Pilgrim Fathers landed at Plymouth,
      Massachusetts (1620). On account of a mistake in reckoning
      the change from Old Style to New Style, it has generally
      been celebrated on the 22d.
      [1913 Webster]

WordNet (r) 3.0 (2006):

forefather
    n 1: the founder of a family; "keep the faith of our
         forefathers" [syn: forefather, father, sire]
    2: person from an earlier time who contributed to the tradition
       shared by some group; "our forefathers brought forth a great
       nation"