quinquennial

Borrowed from Latin quīnquenniālis, from quīnquennium (“5-year period”) + -ālis, from quīnquennis (“5-year”) + -ium (“-ium: forming abstract nouns”), from quīnque (“five”) + annus (“year”) + -is (suffix forming compound adjectives).

• IPA^(key): /kwɪŋˈkwɛ.ni.əl/

quinquennial (not comparable)

1. Of or related to a five-year period.
   • 1879, F. D. Morice, Pindar, chapter 3, page 25:

     By a singular coincidence, the great master of the Dorian lyre was born during the celebration of the Pythia, the quinquennial festival of Apollo […]

   • 2024, Jeremy B. Rudd, A Practical Guide to Macroeconomics, page 56:

     The best data that BEA have come from the quinquennial censuses of business; these are used to “benchmark” the national accounts every five years and to compute new input-output tables.

• pentennial, quintennial, quinquennalian, quinquennal

• quinquennially

• quinquennalia

quinquennial (plural quinquennials)

1. Synonym of quinquennium, a five-year period.
2. A 5th anniversary, particularly
   1. (historical) Synonym of quinquennalia, the festival and religious ritual held in the 5th year of a Roman emperor's reign.

In reference to the Roman festival, sometimes used in the plural to match Latin quinquennalia and provide for the variety of events.

• quintennial, wooden anniversary

• (Roman festival): decennial, vicennial, tricennial