Does the bi prefix mean that it is every second month or twice a month?

  • 1
    It works both ways: merriam-webster.com/dictionary/bimonthly.
    – RK01
    Jul 28, 2015 at 17:55
  • So it is ambiguous?
    – Neil Meyer
    Jul 28, 2015 at 17:56
  • 2
    It's confusing enough that the term is best avoided altogether.
    – phoog
    Jul 28, 2015 at 17:56
  • Semi-monthly would be more syntactically correct for twice a month, but bimonthly is the one commonly used. As RK01 points out, bimonthly should mean every two months, but with usage it has come to mean both.
    – IchabodE
    Jul 28, 2015 at 18:02
  • Discussed already here: english.stackexchange.com/questions/18540/…
    – Sankarane
    Jul 28, 2015 at 18:04

1 Answer 1


Yes, the prefix means two, so bimonthly can mean twice a month or every second month. Always use context, look at the sentence or the surrounding paragraph. That should help you figure out which meaning is being used.

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