Holy day refers to a religious commemorative day or festival:
Liturgical year, determines when feast days, including celebrations of saints, are to be observed List of movable Eastern Christian observances List of movable Western Christian observances Holy day of obligation, in Catholicism, days on which the faithful are expected to attend Mass Festival (Anglicanism), a type of observance in the Churches of the Anglican Communion List of Hindu festivals Buddhist holidays Islamic holidays Jewish holidays Heathen holidays, in Neopaganism Zoroastrian festivals
See also Holiday List of commemorative days, which also contains a number of religious commemorative days and festivals Sabbath