decennalia

Etymology

From Latin decennālia, from decennium (“10-year period”) + -ālia (“-alia: forming the names of festivals”), from decennis (“10-year”) + -ium (“-ium: forming abstract nouns”). Equivalent to decennium + -alia.

noun

The festival and religious rituals celebrating a Roman emperor's 10th year of rule.“Seven pieces celebrate the Decennalia of Arcadius, which were due on Jan. 15, 393.”