What is with words that have forms that end both in -zation and -sation, such as localization and localisation?

Many spell checkers recommend -zation.


7 Answers 7


The "z" is American, the "s" is British. As an American I always use "z" for these words, and apparently many UK spellcheckers do not mark it as wrong and the Oxford English dictionary even gives "organization" as the first spelling, saying (also organisation).

Yet my (US English) Firefox marks the "organisation" variant as misspelled and suggests "organization".

My advice: unless you are writing under guidelines that suggest otherwise, use the "z" form for these words.

  • 5
    Whenever I've marked essays, I've always been perfectly happy with "color"/"colour", "organization"/"organisation". It annoys me that spellcheckers mark the latter spellings of each word as incorrect, and I always change my spellchecker language to British English, just so it covers both. Aug 13, 2010 at 11:26
  • 5
    True. As long as usage is consistent, there's usually no problem either way.
    – Noldorin
    Aug 13, 2010 at 11:30
  • 15
    @Noldorin: The Oxford University Press, and thus the OED -- and other, more practical, dictionaries they publish -- prefers -ize in all cases where -ise is not required (e.g. as in "arise"). Cambridge University Press, and most of the rest of UK publishing, prefers -ise. See "Fowler's Modern English Usage" for more details (under "-ize, -ise"). This is not just a UK vs US, but how you weight the Greek origin vs. French intermediates in the etymology. Wikipedia has a decent summary: en.wikipedia.org/wiki/…
    – Richard
    Aug 13, 2010 at 12:43
  • 7
    But the word arise has neither the suffix -ize nor the suffix -ise. It has the prefix a- plus the stem rise. The word "arise" is not relevant to the discussion of the two spellings of this suffix any more than the end of the word trouble is relevant to the spelling of the suffix -able.
    – Kosmonaut
    Aug 22, 2010 at 18:36
  • 7
    @Richard the problem with preferring -ise is that -ize words always have a Z sound, whereas -ise words vary in pronunciation significantly: anise, promise, treatise, premise, concise, paradise, precise, vise, Denise, elise
    – nohat
    Oct 14, 2010 at 23:53

You often hear people say that -ize is American and -ise is British. While it is certainly true that -ise has become dominant in Britain, -ize is the older spelling, and it once was dominant everywhere. Americans have retained it, while the British have increasingly – since the mid-20th-century I think – favoured -ise. Why, I don't know.

Last time I checked, both the (British) Oxford and Collins dictionaries gave -ize as the first spelling.

I'm British and I always use the -ize spelling, not least because the letter z is so underused, but also because it more accurately indicates its pronunciation (and -ise is plain ugly).

  • 8
    I think this answer would be better if it included a verifiable citation for "-ize is the older spelling" but even so, I am upvoting this for its slightly contrarian bent and the attempt to give 'z' a little more play.
    – John Y
    Feb 16, 2011 at 3:58
  • 5
    @John Y: If you look at the Google Ngram for British English for characterize/characterise, you can see that the z spelling was predominant except between 1850 and 1920. The words organize and localize show similar behaviour. You can do a sanity check by looking at color/colour and seeing that this behaves as expected (color is quite rare in Britain until 1990 or so). Also, as an exception, analyse is still preferred in the U.K. Jul 19, 2011 at 17:43

In publishing, we usually call these -ize and -ise spellings. Some UK publishers prefer -ize, but -ise is the predominant UK style.

See Oxford spelling on Wikipedia. OED prefers -ize spellings.

  • 2
    Just to clarify: OED is the Oxford spelling, so Oxford prefers -ize spellings. With this in mind, it is not so simple to say that -ize is American and -ise is British, as many British use -ize. Se this Wikipedia article (also referenced in comment to the question post) for a thorough discussion on this.
    – awe
    Jan 11, 2011 at 9:22

The US requires -ize. The UK accepts both, but (with the OUP as the main exception) prefers -ise. And this is one of the few cases where "international" English follows the US convention. The ISO favours -ize spellings.

Inbuilt computer dictionaries set to UK English rarely support -ize. Feel free to overrule them.


Apparently, if you see a process of transformation, or as Dictionary.com defines the suffix, "1. To cause to become, resemble or agree with" the word should end with -ize, originating from the Late Latin -izāre, and the greek izein. Or -ize is the rule if there is a smaller word prior to the suffix. -ise is apparently from the latin past participle of words for "take", "see", and "cut" Analyse, for example, comes from (lysis) meaning dissolution. See http://theconversation.com/its-time-to-recognize-and-internalize-the-us-suffix-ize-19828


That is because many spell checkers use American English.

Basically, z is used in North American English (American and Canadian), while s is used in British spellings. You can find explanations for this on the internet — like here, for example: http://www.studyenglishtoday.net/british-american-spelling.html

Which spelling you use, depends on who your audience is. If your writing is to be read mainly or only by speakers of American or Canadian English, use the North American spelling. If it is not, then use the British spelling.

  • '[S] is used in British spellings' is far too broad-brush. It's the choice of about two-thirds of the people in the UK, last time I saw some data. Jan 26, 2022 at 15:22

The New Oxford American Dictionary reports both the words, and the spelling checker used from the Mac OS X (10.6) corrects me when I write organisation.

Considering that US English is set as first language (followed by British English), I would think that organization is the American English word (even though it is not reported by the New Oxford American Dictionary).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.