Nouns

(n)biennial(botany) a plant having a life cycle that normally takes two seasons from germination to death to complete; flowering biennials usually bloom and fruit in the second season

Adjectives

(a)biennial, two-yearhaving a life cycle lasting two seasons“a biennial life cycle”, “parsnips and carrots are biennial plants often grown as annuals”
(s)biennial, biyearlyoccurring every second year“they met at biennial conventions”