holy day of obligation

Noun

1.

holy day of obligation - a day when Catholics must attend Mass and refrain from servile work, and Episcopalians must take Communion

All Saints' Day, Allhallows, Ascension, Ascension Day, Ascension of the Lord, Assumption, Assumption of Mary, August 15, Christian holy day, Christmas, Christmas Day, Dec 25, December 8, Hallowmas, Hallowmass, Immaculate Conception, January 1, November 1, Solemnity of Mary, Xmas