Linguists debate which is better, the "-ise" or the "-ize" ending for verbs (as in "organise" and "organize"). An analysis of the history of word formation provides little resounding support to favour one form or the other.

American English has always favoured the "-ize" ending, while many Britons – almost as a consequence – have preferred to end their verbs in "-ise". In Britain, there did seem to be a move towards using the "-ize" ending more frequently, and indeed Cambridge and Oxford University Presses and The Times have all adopted the "-ize" ending as their preferred forms. In recent years, though, with the advent of spelling checkers (the Microsoft Word British English spelling checker only passes "-ise" forms) and Euro standardisation, the "-ise" form is now gaining ground in Britain and Europe. The rest of the world chooses one or the other, even mixing the two: Canada generally preferring the "-ize" ending, other places more often going for the British form.

A mixed form that is sometimes acceptable allows for the "-ize" form to be used to all stems that are "clear", in other words that are full words when the suffix is removed. Therefore "civilize" is possible as the stem "civil" is a full word, while "baptise" should always be written "-ise" as its stem "bapt" is not a full word.

In British English, the only verbs that must always take an "-ize" ending are:

• to capsize
• to size
• to prize (as in "he prizes his medals").

In American English, the verbs that must always be spelled "-ise" are more numerous and include:

• to advertise
• to advise
• to apprise
• to arise
• to chastise
• to circumcise
• to comprise
• to compromise
• to despise
• to devise
• to disfranchise
• to disguise
• to enfranchise
• to excise
• to exercise
• to improvise
• to incise
• to prise (open) (as in "he prised open the door", though "prize open" may even be seen)
• to promise
• to raise
• to revise
• to rise
• to supervise
• to surmise
• to surprise
• to televise

© Nigel J. Ross, 2003