1. Occurring every second year
   - biennial 
2. Occurring or payable twice each year
   - semiannual, biannual, half-yearly

1. Every two years
   - biennially 
2. Twice a year
   - semiannually

See also: periodic, periodical

• Butazolidin
• butch
• butcher
• butcher block
• butcher board
• Butcher Cumberland
• butcher knife
• butcher paper
• butcher shop
• butcher's broom
• butcherbird
• butchering
• butcherly
• butchery
• Butea
• Butea frondosa
• butea gum
• butea kino
• Butea monosperma
• butene
• Buteo
• Buteo buteo
• Buteo jamaicensis
• Buteo lagopus
• Buteo lineatus