biennial

adj

1. (not-comparable)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.”

2. (not-comparable)Lasting for two years.

noun

1. 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.
2. 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.”