Oxford spelling (or Oxford English Dictionary spelling) is the spelling used by Oxford University Press (OUP), including in its Oxford English Dictionary (OED), and by other publishers who are "etymology conscious", according to Merriam-Webster.
Oxford spelling is best known for its preference of the suffix -ize, rather than -ise, in words like organize and recognize. The spelling affects about 200 verbs and is favoured because -ize corresponds more closely to the Greek root, -izo, of most -ize verbs. Apart from OUP, British dictionary publishers that use Oxford spelling include Cassell, Collins and Longman. It is also used by the London-based scientific journal Nature, The Times Literary Supplement, and by the style guides of international organizations belonging to the United Nations System. In digital documents Oxford spelling may be indicated by the language tag en-GB-oed.
Oxford spelling can be recognized by its use of the suffix ‑ize instead of -ise: organization, privatize and recognizable instead of organisation, privatise and recognisable. The spelling affects about 200 verbs, and is favoured on etymological grounds, in that -ize corresponds more closely to the Greek root, -izo, of most -ize verbs. The suffix -ize has been in use in the UK since the 15th century, and is the spelling variation used in American English. The belief that -ize is an exclusively American variant is incorrect. The OED lists the -ise form of words separately, as "a frequent spelling of -IZE...":
This practice probably began first in French; in modern French the suffix has become -iser, alike in words from Greek, as baptiser, évangéliser, organiser, and those formed after them from Latin, as civiliser, cicatriser, humaniser.
Hence, some have used the spelling -ise in English, as in French, for all these words, and some prefer -ise in words formed in French or English from Latin elements, retaining -ize for those formed < Greek elements.But the suffix itself, whatever the element to which it is added, is in its origin the Greek -ιζειν, Latin -izāre; and, as the pronunciation is also with z, there is no reason why in English the special French spelling should be followed, in opposition to that which is at once etymological and phonetic. In this Dictionary the termination is uniformly written -ize. (In the Greek -ιζ-, the i was short, so originally in Latin, but the double consonant z (= dz, ts) made the syllable long; when the z became a simple consonant, /-idz/ became īz, whence English /-aɪz/.)
The use of -ize instead of -ise does not affect the spelling of words in British English that end in -yse, such as analyse, paralyse and catalyse, which come from the Greek verb λύω, lyo, not from an -izo verb.
Oxford spelling is the official or de facto spelling standard used in style guides of the international organizations that belong to the United Nations System. This includes the World Health Organization, the International Telecommunication Union, the International Labour Organization and UNESCO, and UN treaties and declarations, such as the Universal Declaration of Human Rights.
Other international organizations that adhere to this standard include the International Organization for Standardization (ISO), the World Trade Organization (WTO), the North Atlantic Treaty Organization (NATO), the International Atomic Energy Agency (IAEA), the Organization of the Petroleum Exporting Countries (OPEC), Interpol, the International Committee of the Red Cross, the World Wide Fund for Nature (WWF), Amnesty International and the World Economic Forum.
Oxford spelling is used in a number of academic publications, including the London-based scientific journal Nature, and by The Times Literary Supplement, the Encyclopaedia Britannica and Cambridge University Press. Newspapers and magazines in the UK normally use -ise. The style guide of The Times recommended -ize until 1992, when it switched to -ise. The newspaper's chief revise editor, Richard Dixon, wrote of the change:
This is volcanic ground, with common usage straining the crust of classical etymology. This guidance is a revision of the Greek zeta root ending in the direction of a Latin ending and common usage: apologise, organise, emphasise, televise, circumcise. The only truly awkward result is capsize, which should be left in its Grecian peace.
Language tag comparison
The following table summarizes a few general spelling differences between the four major spelling systems. Note: en-GB simply stands for British English; it is not specified whether -ize or -ise should be used. The language tag en-GB-oed, however, requires the consistent use of -ize and -ization.
behavior (rare) 
program (computer code)
program (computer code)
- Spelling differences: -ise, -ize
- Canadian English spelling
- Macquarie Dictionary (Australian usage)
- Oxford English Dictionary
- Oxford comma
- "ize", Merriam-Webster's Dictionary of English Usage. Merriam-Webster, 1994, p. 568.
- Ritter, R. M. New Hart's Rules. Oxford University Press, 2005, p. 43.
That it affects around 200 verbs, see Upward, Christopher and Davidson, George. "The suffix -IZE/-ISE", The History of English Spelling. John Wiley & Sons, 2011, p. 220.
- McArthur, Tom (ed.). "The -ize and -ise group", Concise Oxford Companion to the English Language. Oxford University Press, 2005, p. 124.
- United Nations Editorial Manual Online, United Nations.
- "-ize or -ise?". Oxford Dictionaries. Oxford University Press. Retrieved 9 August 2013.
"Are spellings like 'privatize' and 'organize' Americanisms?". AskOxford. Oxford University Press. Retrieved 2008-07-14.
- "Which Spelling Standard in English? 'Oxford Spelling'", Pompeu Fabra University.
- Richard Dixon, "Questions answered", The Times, 13 January 2004.
- "Spelling", University of Oxford Branding Toolkit.
- The spelling "analyse" is listed first, ahead of "analyze", by The Winston Canadian Dictionary, Holt, Rinehart and Winston of Canada, Toronto, 1960, 1974.
- The termination -or was formerly endorsed by the Gage Canadian Dictionary.
- The Oxford English Dictionary (1st ed.)
- The Oxford English Dictionary 2nd ed. (20 vols.)
- The Oxford English Dictionary, Oxford: Oxford University Press (latest edition: on WWW)
- United Nations Editorial Manual, New York: United Nations Publications, 1983
- IANA Language Tag Registration Form for en-GB-oed
- AskOxford: Are spellings like privatize and organize Americanisms?
- British Medical Journal: -ize right
- World Wide Words: The endings "-ise" and "-ize"
- Tieken-Boon Van Ostade, Ingrid. An Introduction to Late Modern English. Edinburgh University Press, 2009, p. 38.