Now, people assume that -ise is British and -ize is American, but that isn’t exactly the case. And – of course – it isn’t that simple, either. The one thing that is vitally important, however, is being consistent within a document or documentation.
In British English, either -ise or -ize is acceptable (most people don’t seem to know that. Oxford University Press, for example, use -ize in their house style. If you’re writing articles for journals, it’s important to check for house style on this). In American English, however, it’s -ize all the way. Well, nearly all the way.
Ise is obligatory in some words, and I have to thank New Hart’s Rules for putting this all in one place as an easy reference. So, -ise rather than -ize is obligatory when:
- it forms part of a larger word element, such as -cise (cutting: excise), -vise (seeing: supervise), -mise (sending), or -prise (taking) [if you can think of any examples of the last two with that meaning, please let me know – I presume they are words coming from the French roots mener and prener but apart from that I’m stumped for examples that include the meaning sending or taking]
- it corresponds to a noun that has an s in the stem: advertisement – advertise; television – televise
Common words that must use -ise in American and British English:
advertise, advise, apprise, arise, chastise, circumcise, comprise, compromise, demise, despise, devise, (dis)enfranchise, disguise, enterprise, excise, exercise, improvise, incise, merchandise, premise, prise (open), revise, supervise, surmise, surprise, televise
When we move on to the -yse / -yze debate, it’s much more simple: -yse in British English, -yze in American, so analyse vs. analyze, etc.
This issue comes up a lot for me, because I work with many students who, although studying in the UK, have American English as their standard language in Word and use American spellings throughout. Except when they don’t. If they mix them up, as they invariably do, well, I used to ask which they preferred but now I just pick the most common version they use and tell them that I’ve done that.
But the most important things are to
- Obey house style, if there is one (particularly important if you’re writing journal articles)
- Be consistent.
- If you are quoting from a source which uses a different spelling from your required one (e.g. you are working with -ise and it uses -ize), leave the word in the original form in which it was printed in a direct quotation. See more in my posts on quoting sources [coming soon].