The Myth of the British -ise Ending

If you’ve ever written or edited in British English, you may have come across the old maxim that in the UK, -ise endings are a must. You may even have heard that -ize endings should be shunned to “avoid Americanisation”. However, while it’s true that US English uses -ize endings as a standard, it’s hard to point to what the standard is in the UK, where both -ise and -ize have been, and continue to be, used.

What are -ise/-ize endings?

This is a question of how to spell words such as “realise”, “mobilise”, and “organise” (or “realize”, “mobilize”, and “organize”). It also affects words derived from these, such as “realising”, “mobilisable”, and “organisation” (or “realization”, “mobilizable”, and “organization”). Note that there is no difference in the pronunciation – whether spelled with an “s” or “z”, the ending syllables are all said the same way.

In the US, the choice is simple – only -ize endings have been acceptable there since the spelling reforms of the 19th century. However, UK styles vary, with some adopting -ize and others -ise.

A long history of British ambivalence

The truth is that although -ize endings were chosen as a standard in the US, they weren’t invented there. As David Shariatmadari notes in an article in the Guardian defending the use of “realize” by King Charles III (then Prince Charles) in a letter to President Macron of France in 2019, the z’s in -ize endings came from the -izāre and -izein endings of Greek and Latin words, respectively, that entered into English. The complication is that words with a similar formation were also adopted from French, whose original -iser endings influenced the -ise endings in the English versions. A mixture of -ize and -ise spellings therefore abounded in the UK. Neither could have been said to be more British as that time.

The origin of the British -ise myth

It seems fair to say that there was a degree of anti-British (or at least pro-American) sentiment behind Noah Webster’s spelling reforms in the US, which included the adoption of -ize as one spelling to rule them all. It seems that after the US went all-in on -ize, some in Britain then began to favour -ise endings as being demonstrably non-American, and therefore more British.

It’s just one example of people wanting to defend their language against outside influence. For an example, we need look no further than Prince Charles’s correspondent, President Macron, who has decried the influence of British and American English on French. However, it seems unusual that in this case, the real influence on British English came not outside, from the New World, but from its own Latin and Greek foundations.

Current examples of styles

While there has been a move against -ize endings, the UK never went through a process of reform and standardisation to match that in the US, and variant spellings and alternative forms were never fully tamed. So while many rallied around -ise, others did not, including grammarians who cited the Greek and Latin origins that make -ize endings more “correct”.

To this day, then, both -ise and -ize are acceptable in British English. Within a particular document or publication, it is usual to consistently adopt one or the other, though, as part of the style. Many organisations pick one option to apply in all their output. For example, BBC News prescribes -ise endings in its style guide, as do the Guardian and the Observer, while the UK Government style guide goes as far as to refer to this as “UK English spelling”. Conversely, Bloomsbury Publishing Academic and Professional Division is among those that calls for -ize endings, as stipulated in its House Style Guidelines for Authors and Editors.

To underscore the lack of standardisation, while the University of Cambridge firmly opts for -ise, the AuthorHub Style Guide of its publishing department Cambridge University Press grants the flexibility of either -ise or -ize. For an even starker contrast, consider that the University of Oxford's style guide opts for -ise endings, whereas Oxford University Press (OUP) prefers -ize endings – part of what’s known as “Oxford Style” – as reflected in its Style Guide for Authors, the Oxford English Dictionary and New Hart’s Rules: The Oxford Style Guide.

Unlike in the US where certain styles are widely adopted, such as the Chicago Manual of Style for fiction publishing, no one style guide dominates in the UK to the saem extent. That may change in the future, but for now, -ise and -ize endings remain acceptable variant spellings in British English. The choice may be dictated by the publisher, or the author may be free to follow their own preference. But for any given text, a choice should be made and applied consistently throughout.


As a final point, it’s worth noting that the -ize/-ise choice only applies to words such as those above. It doesn’t apply to words from outside that category. Therefore, some words are universally spelled with “ise” at the end, such as “wise”, “exercise”, “advise”, “noise”, “prise” (as in “prise open”). Others always end “ize”, including “size”, “maize”, “capsize”, “seize”, “prize” (as in “win a prize”). That’s important for the editor or proofreader wanting to bring consistency to a document using a mixture of -ise and -ize endings – a simple search and replace to switch all examples of -ise to -ize, say, could yield unfortunate results.

A related spelling to be aware of is “analyse”/“analyze”. It’s spelled with a “z” in the US, but always with an “s” in British English, even if -ize endings are being used elsewhere.

Style for this article: British English, -ise endings, serial comma, double quote marks for Internet use.
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