high day 
noun British
The day of a religious festival.The Bible describes two kinds of Sabbath whereon all customary work was precluded: the regular weekly Sabbaths which were fixed DAYS, ‘the seventh day of the week’, and special Sabbaths or high days that are fixed DATES, and can fall upon any day of the week....
- For high days I have a thimble-sized glass to drink port.
- On high days he would have been carried to the temple for celebrations and sacrifices.
Phrases
high days and holidays