I. |trīə|terik noun
( -s )
Etymology: Late Latin trieterica, from feminine of trietericus occurring every third year
: a trieteric festival especially in honor of Bacchus
II. adjective
Etymology: Latin trietericus, from Greek trietērikos, from trietēris triennial festival (from tri- three + etos year) + -ikos -ic — more at tri- , wether
: occurring in alternate years — used of an ancient Greek rite