Oxford Spelling

Oxford spelling (or Oxford English Dictionary spelling) is the spelling used by Oxford University Press (OUP), including in its Oxford English Dictionary (OED), and other publishers who are "etymology conscious," according to Merriam-Webster. Apart from OUP, British dictionary publishers that use it include Cassell, Collins and Longman. In digital documents it 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 16th century, and continues to be the spelling used in American English. Since the 1990s, -ise has become more common in the UK, with the result that -ize may be regarded incorrectly as an exclusively American variant. The OED lists the -ise form of words separately, as "a frequent spelling of -IZE...". The OED explains its use of -ize as follows:

n mod.F. the suffix has become -iser, alike in words from Greek, as baptiser, évangéliser, organiser, and those formed after them from L., as civiliser, cicatriser, humaniser. Hence, some have used the spelling -ise in Eng., as in French, for all these words, and some prefer -ise in words formed in French or Eng. from L. elements, retaining -ize for those of Gr. composition. But the suffix itself, whatever the element to which it is added, is in its origin the Gr. -ιζειν, L. -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 Gr. -ιζ-, the i was short, so originally in L., but the double consonant z (= dz, ts) made the syllable long; when the z became a simple consonant, (-idz) became īz, whence Eng. (-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.