From Bishop Farrell's Blog (www.bishopkevinfarrell.org):
Next week we celebrate All Hallows Day. The term is not common in America, but it is more familiar to Irish and English Catholics as the name for the Feast of All Saints. The word “hallow” means holy, or more specifically, making things holy as in the Lord’s Prayer, “hallowed be thy name.”
All Saints or All Hallows on November 1st was established in the 8th century by Pope Gregory III to honor “the holy apostles and all saints, martyrs and confessors.” They were made “hallow” by the witness of their lives. They are honored or venerated because of the heroic lives they led.
All Saints is one of the twin observances in early November. The other is All Souls Day, in which the Church remembers and prays for the deceased, often referred to as the “poor souls,” who “have not yet been purified of the punishment for sin.” (Catechism of the Catholic Church #1475)
For full article: All Hallows Day, by Bishop Kevin Farrell