vigintennial
English
Etymology
From viginti- (“twenty”) + -ennial (“yearly”), from Latin vīgintī (“twenty”) and -enniālis, from annus (“year”) + -is (“forming compound adjectives”) + -ālis (“-al: forming adjectives”).
Adjective
vigintennial (not comparable)
References
- “vigintennial, adj.”, in OED Online , Oxford: Oxford University Press, launched 2000.