What is Biennial ?
Biennial is (adj) 1. (of a plant) which flowers in its second year of growth and then dies 2. (of an event) which happens every two years The athletics competition is a biennial event. (NOTE: Do not confuse with biannual.) (noun) a plant which flowers in its second year of growth and then dies We plant biennials at the back of the flowerbed and annuals in front.
source: Easier English, Student Dictionary Upper Intermediate Level