heortology
The study of religious festivals.
uncountable
For the same reason, in accordance with the meaning of the term "Heortology," he has concerned himself with those festivals alone which are publicly celebrated, or were so celebrated formerly.
Where it comes from
From German Heortologie, from Ancient Greek ἑορτή (heortḗ, “festival”) + -ology.
Adapted from the Wiktionary entry heortology (CC BY-SA 4.0).