pref.
- Two: biform.
- Both: binaural.
- Both sides, parts, or directions: biconcave.
- Occurring at intervals of two: bicentennial.
- Usage Problem. Occurring twice during: biweekly.
- Containing twice the proportion of a specified chemical element or group necessary for stability: bicarbonate.
- Containing two chemical atoms, radicals, or groups: biphenyl.
[Latin bis, bi-, twice, and bīnī, two by two.]
USAGE NOTE Bimonthly and biweekly mean "once every two months" and "once every two weeks." For "twice a month" and "twice a week," the words semimonthly and semiweekly should be used. Since there is a great deal of confusion over the distinction, a writer is well advised to substitute expressions like every two months or twice a month where possible. However, each noun form has only one sense in the publishing world. Thus, a bimonthly is published every two months, and a biweekly every two weeks.
