† biˈennalObs. [ad. late L. biennāl-e (sc.officium), neuter of biennālis of two years (see next).] The saying of masses for a departed soul during the period of two years. 1362Langl.P. Pl. A. viii. 156 Bienals [v.r. biennales, byennals] and Trienals and Busschopes lettres.