Note that, authorize and authorise come from Old French autoriser which comes from Medieval Latin auctorizare. Moreover, there are two groups of -ise words here.
Originally Posted by fabiopepper
-ise and ize
The first group consists of words which are always spelled with -ise in all varieties of English. The most frequent verbs in this group are advertise, advise, apprise, chastise, circumcise, comprise, compromise, despise, devise, disguise, excise, exercise, improvise, supervise, surmise, surprise and televise, to which we may add the nouns demise, enterprise, franchise and merchandise, some of which are occasionally used as verbs. These words do not contain the Greek suffix -ize and may never be spelled with -ize. British writers attempting to use American spelling sometimes slip up here and write, for example, *advertize, which is never acceptable. Read more here: 'ise' vs 'ize'
The Endings -ise and ize
The broad rule is that the -ize forms are standard in the US, but that -ise ones are now usual in Britain and the Commonwealth in all but formal writing. For example, all British newspapers use the -ise forms; so do most magazines and most non-academic books published in the UK. However, some British publishers insist on the -ize forms (Oxford University Press especially), as do many academic journals and a few other publications (the SF magazine Interzone comes to mind). Most British dictionaries quote both forms, but — despite common usage — put the -ize form first.
All the best.
The original form, taken from Greek via Latin, is -ize
. That’s the justification for continuing to spell words that way (it helps that we say the ending with a z
sound). American English standardised on the -ize
ending when it was universal. However, French verbs from the same Latin and Greek sources all settled on the s
form and this has been a powerful influence on British English. The change by publishers in the UK has happened comparatively recently, only beginning about a century ago (much too recently to influence American spelling), though you can find occasional examples of the -ise
form in texts going back to the seventeenth century. Read more here: World Wide Words: The endings '-ise' and '-ize'