octennial adjective.
[ɒk'tɛnɪǝl] M17.[from late Latin octennium period of eight years, formed as OCTO- + annus year: see -AL1. Cf. biennial etc.]Of or pertaining to a period of eight years; lasting for eight years; occurring every eight years.
■ octennially adverb every eight years
M19. [TahlilGaran] English Dictionary ▲