"Semi-annually" describes an event that recurs every 6 months. Is there a similar term for an event that recurs every 3 months? (I'm guessing that "semi-semi-annually" isn't the correct answer.)

More importantly, is there a resource or table somewhere that I can use in the future to construct prefixes for other intervals shorter than a year?

  • 1
    Note that if you wished to employ multiple prefixes the relevant analogy would be in music: quaver, semiquaver, demisemiquaver, hemidemisemiquaver. That is, you would not repeat semi- but add demi-.
    – MetaEd
    Jan 18, 2013 at 18:03

5 Answers 5


This is not exactly a prefix but the word does indeed refer to an event that occurs four times a year. And the word is "Quarterly".

  • This got you so many upboats?? why was i not here earlier?? sobs
    – Mahesh
    Jun 21, 2012 at 15:45
  • 2
    Blame George Edison. :P
    – jokerdino
    Jun 21, 2012 at 15:48

More importantly, is there a resource or table somewhere that I can use in the future to construct prefixes for other intervals shorter than a year?

Not really, because commonly used ones are often exceptions to rules. However, you now have a good set:

  • Annually (and the multiplicators)
  • Bianually
  • Quarterly
  • Monthly (there should be a word for every two months)
  • Fortnightly
  • Weekly


Now you only have problems if you need to define every 6 weeks or suchlike.

  • 4
    Sesquimonthly would be a close approximation for 6 weeks.
    – zzzzBov
    Jan 23, 2012 at 14:43
  • @zzzzBov - I think using that in normal conversation might prove interesting. There are words for a range of different periods, but whether they actually work in communication is another matter. Jan 23, 2012 at 15:25
  • 1
    When the purpose is for unambiguous communication, "6 weeks" would obviously be the preferred descriptor. Not all language is meant to be unambiguous simple communication; poetry and music often choose words with a richer meaning.
    – zzzzBov
    Jan 23, 2012 at 15:30
  • 1
    There's potentially confusion around biannual; also consider semiannual.
    – josh3736
    Jan 23, 2012 at 15:48
  • @zzzzBov I am not saying that you are wrong, just that, as you point out, the aim is clear communication. Jan 23, 2012 at 16:55



doesn't suffice,


is probably closest in spirit to "semi-annually" (although I would prefer "biannual" to this anyway)

You should be able to construct such a table reasonably easily.

weekly           every week
bi-weekly        every two weeks
tri-weekly       every three weeks
monthly          every month
bi-monthly       every two months
tri-monthly      every three months
biannual         every six months


  • 2
    biweekly ( and monthly ) as well as tri- suffer from a confusion between meaning every two weeks, or twice a week. I would be very reluctant to use them. Jan 23, 2012 at 15:27

A smattering of people are using the term semibiannual online to designate one quarter of the year.


You might make use of Latin prefix quadri- quadru- E.g


  • 8
    Quadrennial means "every four years", like biennial means "every two years". Since biannual means "twice a year" (well, according to most people...), you might get away with quadriannual... Jan 23, 2012 at 9:06
  • @lonesomeday, both quadri- and quadru- means: four or four times. Longman
    – Mustafa
    Jan 23, 2012 at 9:41
  • 3
    @George Edison, you may also use "trimonthly"
    – Mustafa
    Jan 23, 2012 at 9:55
  • 1
    @Mustafa, the issue isn't the "quadri-" it's the "ennial" vs "annual". The former uses the count for the number of years, the latter uses the count for the occurrences per year.
    – zzzzBov
    Jan 23, 2012 at 14:45
  • @zzzzBov, could you please post a reference "annual" and "ennial" are different words and they are also different in meaning?
    – Mustafa
    Jan 23, 2012 at 14:56

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