Biweekly / Fortnightly / Twice weekly
UsageBiweekly can mean every two weeks or twice a week. Use fortnightly or every two weeks for the first meaning, and twice weekly or twice a week for the second.
Biweekly
Use when
Only when your audience has an established convention or the schedule is immediately clarified.
Example
“The biweekly meeting takes place every other Wednesday.”
Fortnightly
Use when
You mean once every two weeks.
Example
“The working group meets fortnightly on alternate Wednesdays.”
Twice weekly
Use when
You mean two times each week.
Example
“The operations call is held twice weekly, on Tuesday and Friday.”
Quick check
biweekly without clarification, fortnightly used for twice a week, ambiguous recurring deadline
Usage note
Every two weeks is often clearer than fortnightly for international audiences. State the actual days when the schedule affects deadlines, payroll or attendance.