vicennial /vī-senˈyəl/

1. Lasting, or coming at the end of, twenty years
2. Occurring every twenty years

• palsier
• palsies
• palsiest
• palstaff
• palstaffs
• palstave
• palstaves
• palsy
• palsying
• palsy-walsy
• palter
• paltered
• palterer
• palterers
• paltering
• palters
• paltrier
• paltriest
• paltrily
• paltriness
• paltrinesses
• paltry
• paludal
• paludament
• paludaments