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

• billed
• billet
• billet-doux
• billeted
• billet-head
• billet-heads
• billeting
• billets
• billets-doux
• billfish
• billfishes
• billfold
• billfolds
• billhead
• billheads
• billhook
• billhooks
• billiard
• billiard ball
• billiard balls
• billiard cloth
• billiard cloths
• billiard cue
• billiard cues
• billiard-marker