bil·lionth 
(bĭlyənth)
(bĭlyənth)n.
1. The ordinal number matching the number one billion in a series.
2. One of a billion equal parts.
billionth adj. & adv.
- bioluminescence
- bioluminescent
- biolysis
- biolytic
- biomagnetism
- biomagnification
- biomarker
- biomass
- biomaterial
- biomathematical
- biomathematician
- biomathematics
- biome
- biomechanical
- biomechanically
- biomechanics
- biomedical
- biomedical engineering
- biomedicine
- biometeorology
- biometric
- biometrical
- biometrically
- biometrics
- biometry