1911 Encyclopædia Britannica/Passion Week

PASSION WEEK, the fifth week in Lent, beginning with Passion Sunday (dominica passionis or de passione domini), so called from very early times because with it begins the more special commemoration of Christ’s passion. Passion week is often incorrectly identified with Holy week (q.v.). In the north of England Passion Sunday was formerly known as Carle or Carling Sunday, a name corrupted from “care,” in allusion to the sorrowful season which the day heralds. It was the universal custom in medieval England to eat on this Sunday a grey pea steeped and fried in butter, which came to be called from its association “Carling Nut.”