Easter

Easter, an important festival of the Church commemorating the resurrection of Christ; held on the first Sunday after the first full moon of the calendar which happens on or next after 21st of March, and constituting the beginning of the ecclesiastical year; the date of it determines the dates of other movable festivals; derives its name from Eastre, a Saxon goddess, whose festival was celebrated about the same time, and to which many of the Easter customs owe their origin.

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