biennial
adjective
bi·en·ni·al
| \ (ˌ)bī-ˈe-nē-əl
\
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Definition of biennial
1
: occurring every two years
a biennial celebration
2
: continuing or lasting for two years
specifically, of a plant
: growing vegetatively during the first year and fruiting and dying during the second
Biennial herbs flower in their second year.