Meaning of DUODECENNIAL in English

|d(y)ü(ˌ)ō+ adjective

Etymology: Late Latin duodecenni um period of 12 years (from Latin duodecim twelve — from duo two + -decim, from decem ten — + -ennium, from annus year) + English -al — more at two , ten , annual

: occurring once in 12 years

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.