Definition of Easter

A feast of the Christian church held in memory of the Saviour’s resurrection. The Greeks and Latins call it “pascha” (passover), to which Jewish feast our Easter answers. This feast has been annually celebrated since the time of the apostles, and is one of the most important festivals in the Christian calendar, being that which regulates and determines the times of all the other movable feasts.

That's the definition of Easter in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.