bi-, semi-

Forms solid compounds except when followed by a capital letter or i, or when unreadable.

To avoid confusion, the following uses are strongly recommended:

            semiweekly or better twice a week

            biweekly or better every two weeks or every other week

            semimonthly or better twice a month

            bimonthly or better every two months or every other month

            semiannual or better twice a year

            biennial or better every two years or every other year