tri ‧ en ‧ ni ‧ al /traɪˈeniəl/ BrE AmE adjective
[ Date: 1500-1600 ; Language: Latin ; Origin: triennis , from triennium 'three years' , from tri- + annus 'year' ]
happening every three years ⇨ annual
tri ‧ en ‧ ni ‧ al /traɪˈeniəl/ BrE AmE adjective
[ Date: 1500-1600 ; Language: Latin ; Origin: triennis , from triennium 'three years' , from tri- + annus 'year' ]
happening every three years ⇨ annual
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012