We have two words for events occurring in periods of years - biannual meaning twice a year, and biennial meaning once every two years.

However, my colleagues talk about having meetings biweekly. This causes a lot of confusion, since it can mean either once every two weeks or twice a week.

We can use fortnightly to indicate once every two weeks and help disambiguate that way. Are there any other words we could use which could help, particularly words which mean "twice a week"? I'm looking particularly because some of my colleagues speak English only as a second language, and find fortnightly difficult to remember.

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    Related: english.stackexchange.com/q/18540/8019 (which mentioned "semiweekly"). Dec 5, 2011 at 14:08
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    The 'semi-' prefix is pretty commonly understood to mean 'half' so that 'semi-weekly' means twice a week straightforwardly (but somewhat strangely..is that spaced like Monday/Thursday, or Monday/Friday?). It is 'bi- that confuses most people...um...gets used for both 'half' and 'twice'. Anyway, what's wrong with 'twice a week' and 'every two weeks'?
    – Mitch
    Dec 5, 2011 at 16:27
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    I use the idiom every other week in this situation.
    – Gabe
    Dec 5, 2011 at 17:37
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    @Gabe That means, "not this week", right? Dec 5, 2011 at 17:51
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    @curiousdannii I was a programmer at the time I wrote this, and looking to see if there was a succinct expression I could use for a class name. Just because it's of little benefit to you doesn't mean it isn't of benefit to someone else. There's a reason I asked.
    – Lunivore
    Aug 31, 2015 at 14:43

5 Answers 5


Avoid biweekly altogether. Use fortnightly for "once every two weeks", and twice a week for, well, "twice a week".

Not everything has to be a single word, so don't be afraid to use more than one word when you want to use clear, understandable, unambiguous language.

If they have problems with fortnightly, use every other week, or let them into a little secret: fortnight comes from "fourteen nights", or two weeks.

Edit: From the comments it's clear many Americans won't understand or are uncomfortable with fortnight so, to be safe, use the aforementioned every other week.

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    +1. If using a word introduces unwanted ambiguity, just don't use that word! Dec 5, 2011 at 13:23
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    Yeah, don't use 'fortnight'. Unless you intentionally want to be not understood or sound like you woke up from a 200 year coma.
    – Mitch
    Dec 5, 2011 at 13:23
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    @Mitch I believe "fortnight" is quite commonly used in the UK still.
    – Kit Z. Fox
    Dec 5, 2011 at 13:25
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    I do come from the UK and it's an ordinary, commonly used word here.
    – Lunivore
    Dec 5, 2011 at 13:37
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    I think the word fortnight is familiar to many, even in the US. However, if there is already language barrier in play, it may better to err on the side of clarity. Unless "fortnight" is commonly used in your environment, better to use some variation of "every other week" instead.
    – Leigh
    Dec 5, 2011 at 15:20

Technically, semiweekly is the term that you're looking for. But if you're trying to avoid ambiguity, then go with something like "twice a week" like Hugo suggested. Too many people get biweekly and semiweekly confused.

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    This should be marked as the answer to the original question "Are there any other words we could use which could help, particularly words which mean 'twice a week'?". Semiweekly is defined as "occurring twice a week". Dec 9, 2016 at 20:30
  • Semiweekly immediately makes me think of "every two weeks". I see the word "weekly" is like a rate, and thus semi- halves that rate from every one week to every two weeks. Semi-weekly instead of semiweek-ly. (English is not my first language, but I learned something new today.)
    – Nuclear241
    Jul 26 at 7:24

I agree with those who suggested "fortnightly." If someone feels that it's antiquated or "odd," that is their problem! It's a great word. Besides the ambiguity of the words "bi-weekly" or "bi-monthly," I think that they are esthetically ugly and artificial words that detract from the English language. I like to keep my Latin and Germanic mixing to a minimum. Try "twice weekly," if "fortnightly" doesn't do it for you.

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    Careful now! Ugly is Germanic and artificial is from Latin :)
    – Hugo
    Dec 6, 2011 at 22:38
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    @Gavin: I think your last sentence sums up why there's some confusion with the word.
    – Julia
    Dec 8, 2011 at 7:22
  • Hugo: touche! There's another one... Julia: I was making a subtle joke...attempting to, anyway. Dec 9, 2011 at 1:24

Strangely, although bicentennial, bilingual, and bipedal (among many other actual and imagined bi-prefixed words) would never be understood as referring to half- century, language, foot, etc. phenomena, biannual (or biennial) or bimonthly or biweekly (and probably bi-daily, if anyone ever tried it out on people) do elicit that interpretation (perhaps largely among the semi-, but certainly not the bi-, literate). Dictionary.com offers the following highly laudable advice:

"Since bi- can be taken to mean either “twice each” or “every two,” a word like biweekly can be understood as “twice each week” or “every two weeks.” To avoid confusion, it is better to use the prefix semi- to mean “twice each” (semiannual; semimonthly; semiweekly) or the phrase twice a or twice each (twice a month; twice a week; twice each year), and for the other sense to use the phrase every two (every two months; every two weeks; every two years)."

As for the claim that "every two" (or "every other") years/months/weeks/days beats biennial/bimonthly/biweekly/bidaily, it fails to meet the immediately-intelligible test that ought to govern all linguistic prescriptions.

  • Voted down because you shouldn't accuse people of being semi-literate without very good reason. (Against SE policies.)
    – Stuart F
    Jun 9 at 9:27

I might suggest being careful with biannual as well. It is sometimes used for meetings held once every two years. There are three times as many Google hits for semi-annual as bi-annual, so that could indicate a lack of confidence in using bi-.

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