moveable feast

English Thesaurus

1. a religious holiday that falls on different dates in different years (noun.time)

hypernym	:	feast day, fete day,
definition	:	a day designated for feasting (noun.time)

hyponym	:	easter,
definition	:	a Christian celebration of the Resurrection of Christ; celebrated on the Sunday following the first full moon after the vernal equinox (noun.time)

hyponym	:	feast of the unleavened bread, passover, pesach, pesah,
definition	:	(Judaism) a Jewish festival (traditionally 8 days from Nissan 15) celebrating the exodus of the Israelites from Egypt (noun.time)