biennial /baɪˈɛn.i.əl/adjective 2noun 2forms 1 adjective2 •Happening every two years.This is a marked difference from the task force’s previous guidance, which was to start biennial mammograms by age 50. — 2024 •Lasting for two years. noun2 •An event that happens every two years.The famous Biennial was won by Earl of Dartrey, a light, peacocky horse, who was, perhaps, better than he looked. — 1891 •A plant that requires two years to complete its life-cycle, germinating and growing in its first year, then producing its flowers and fruit in its second year, after which it usually dies. formsbiennials
