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I have trouble understanding why some words change "s"-es to "z"-s from BE to AE and some not. For example:

  • analyse -> analyze
  • characterise -> characterize
  • hypnotise -> hypnotize


  • compromise -> compromise

Is there any rule to this?

Slightly related: Why Isn't Citizen 'Citisen' in British English?

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related: english.stackexchange.com/q/707/8019 (and others) – TimLymington Sep 4 '12 at 9:36
Seemingly irrelevant, there is the fascinating Barthes S/Z. Not to give anything away, but this may explain a lot about the perceived cultural differences between the US and the UK. – Mitch Sep 4 '12 at 13:24
Oxford University Press and Cambridge University Press use the -ize spelling where it corresponds to the Greek etymology (see Andrew Leach’s answer). So, it is not exactly BE versus AE (though the division is broadly accurate). – Daniel Harbour Sep 4 '12 at 15:11
That isn't even slightly related, because BE came first. British spelling comes from wherever it came from, and 's'/'z' accordingly; American spelling changes many of those to the more phonetic 'z'. – Ollie Ford Jul 30 '14 at 21:52
@OllieFord BrE did not 'come first'; rather, when the Americans left we spoke and wrote the same way, and after they left each started diverging from the original point. In any case, the z is recent in -yse but not -ize, -yse from Greek -lysis and -ize from Greek -izein, Latin -izare. The spelling -ise comes from French -iser. – Nothing at all Jul 1 at 17:18
up vote 8 down vote accepted

Etymonline contains useful information.

suffix forming verbs, M.E. -isen, from O.Fr. -iser, from L.L. -izare, from Gk. -izein. English picked up the French form, but partially reverted to the correct Greek -z- spelling from late 16c. In Britain, despite the opposition (at least formerly) of OED, Encyclopaedia Britannica, the “Times of London,” and Fowler, -ise remains dominant. Fowler thinks this is to avoid the difficulty of remembering the short list of common words not from Greek which must be spelled with an -s- (e.g. advertise, devise, surprise).

That last list includes compromise too, as that does not have a Greek root.

The one I’ve had most contact with is baptise/baptize which comes directly from the Greek baptizein and presumably should be spelled with z.

As someone with an interest in letterforms, I've always found z an anomalous letter (the thick stroke goes in the wrong direction) and I far prefer the appearance of these words spelled with an s. That may also be a contributory factor (as well as Fowler’s “difficulty”), even if only subliminally.

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english.stackexchange.com/questions/707/… appears to be a duplicate but the Greek root is only mentioned in one comment. – Andrew Leach Sep 4 '12 at 9:38

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