biennial /bī-enˈi-əl or -enˈyəl/

1. Lasting two years
2. Happening or appearing once in two years

1. A plant that flowers and fruits only in its second year, then dies
2. An event taking place or being celebrated every two years

biennˈially adverb

• knacks
• knackwurst
• knackwursts
• knacky
• knag
• knaggier
• knaggiest
• knagginess
• knagginesses
• knaggy
• knags
• knaidel
• knaidlach
• knaidloch
• knap
• knap-bottle
• knap-bottles
• knapped
• knapper
• knappers
• knapping
• knapping-hammer
• knapping-hammers
• knapple
• knappled