bi-
Pronunciation: /bʌɪ/
combiningForm
- occurring twice in every one or once in every two: bicentennial
- lasting for two: biennial
- doubly; in two ways: biconcave
- Chemistry (in names of compounds) containing two atoms or groups of a specified kind: biphenyl
- Chemistry denoting an acid salt: bicarbonate
- Botany & Zoology (of division and subdivision) twice over: bipinnate
Origin:
from Latin, 'doubly, having two'; related to Greek di- 'two'
The meaning of bimonthly (and other similar words such as biweekly and biyearly) is ambiguous. Such words can either mean ‘occurring or produced twice a month’ or ‘occurring or produced every two months’. The only way to avoid this ambiguity is to use alternative expressions like every two months and twice a month. Biannual and biennial are also confusing: biannual means ‘occurring twice a year’ and biennial means ‘occurring every two years’.