Meaning of Forefathers' Day

Fore'fathers' Day"

Pronunciation: [key]
  1. the anniversary of the day (December 21, 1620, in Old Style December 11) on which the Pilgrims landed at Plymouth, Mass. Owing to an error in changing the date from the Old Style to the New, it is generally observed on December 22.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.