tri|e|ter|ic «TRY uh TEHR ihk», adjective, noun.
–adj.
(in ancient Greece) occurring or held every third year (in the ancient reckoning, every alternate year), as certain festivals.
–n.
a trieteric festival.
╂[< Latin trietēricus < Greek trietērikós, ultimately < tri- three + étos year]
Useful english dictionary. 2012.