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This has confused me to no end. Often, I find myself unable to figure out how to spell a verb simply because of the -ise/-ize ending. I see verbs such as realise, strategize and other words such as these that all have one of these two endings and confuse me with how there hasn't been any sort of noticeable rule or pattern to figure out which spelling to use.

How do I tell if a word ends in -ise or -ize?

marked as duplicate by Damkerng T., Nathan Tuggy, snailboat, Usernew, shin Dec 1 '15 at 9:48

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  • Generally speaking, in American English, verbs take the -ize ending, and in British and Australian English they take the -ise ending. So to answer your question, There are always exceptions to the rule, but if you use these endings depending on where you live, you should be right. – Riley Francisco Dec 1 '15 at 7:21
  • @Texenox, the links in my first comments in the old question should be useful: ell.stackexchange.com/questions/61147/…. – Damkerng T. Dec 1 '15 at 7:45

There is one more to 'ise' and 'ize'. It is 'yse'!

Straight from the OxfordDictionaries:

Many verbs that end in -ize can also end in -ise: both endings are correct in British English, though you should stick to one or the other within a piece of writing. For example: finalize/finalise; organize/organise; realize/realise.

But there is a small set of verbs that must always be spelled with -ise at the end and never with -ize. The main reason for this is that, in these words, -ise is part of a longer word element rather than being a separate ending in its own right. For example: -cise (meaning ‘cutting’) in the word excise; -prise (meaning ‘taking’) as in surprise; or –mise (meaning ‘sending’) as in promise. Here are the most common ones:


There are also a few verbs which always end in -yse in British English.

and so on...

In American English, they are all spelled with the ending -yze

You can read more about the use of ‘ize’ and ‘ise’ on the Oxford Dictionaries blog. Here you will find more information about the historical usage of ‘ize’ and ‘ise’ and the difference between the two in the context of British English and American English.

  • Thanks, I suppose, but the problem is, I've seen a couple of -ize verbs too which seem to be used in British English, like strategize. What's the deal with that? – nine Dec 1 '15 at 7:44
  • 1
    Quite possible. Not all may follow this strictly. But if you go by books, it should be 'strategise' in BrE – Maulik V Dec 1 '15 at 7:47
  • The deal is that us Brits get exposed to so much American media that we sometimes get our own spelling wrong. – ssav Dec 2 '15 at 13:44

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