In atrial fibrillation, assuming that you use digitalis, do you digitalise or digitalize? Well, contrary to common belief in Britain, the appropriate English spelling for such words is with -ize, rather than -ise.

Many such words originally derived from Greek verbs that ended in -ιζειν (-izein), a suffix that was added to a noun to create a verbal infinitive, either transitive (meaning “to make or conform to, or treat in the way of, the thing expressed by the derivation,” such as anatomize) or intransitive (“to act some person or character, do or follow some practice,” such as philosophize). Then the same was done in Latin, using the suffix -izare to make a noun into a verb, usually transitive (meaning “to make [that which is expressed by the derivation],” such as immortalize). English words that derive from these should be spelled with -ize. Other verbs that derive from nouns that are neither Greek nor Latin also take -ize. These include verbs formed from proper names (such as mesmerize and Americanize) and from names of chemical compounds (such as oxidize and digitalize).

The box shows the exceptions to the -ize rule, and the etymological reasons. None of the words is from Greek, and they mainly derive directly from verbs rather than from nouns plus -ise.

So how often do people digitalize or digitalise? When I searched Medline the citations numbered 778 and 154 respectively—that is, 83% in favour of -ize, partly due to the North American influence (see table). In contrast, nouns that end in -lysis should form verbs ending in -lyse, but -lyze is often seen in American texts. The Medline occurrences of -lyse or -lyze words (ana-, auto-, bacterio-, cata-, cyto-, dia-, electro-, h(a)emato-, h(a)emo-, histo-, hydro-, leukocyto-, neuro-, para-, photo-, plasmo-, proteo-, radio-, thermo-, zymo-, and lyse itself) are given in the table and show the heavy North American influence.

So why is -ise an alternative to -ize? Well, blame the French—they changed the Latin -izare to -iser. Of course, English wouldn't be English if there weren't some words that end in -ize that can't be spelled -ise: assize, capsize, Louis-Seize, Louis-Treize, prize, seize, and size.

So all in all, as you might say, the -ize have it.

Word	Origin
Advertise	Latin -vertere Old French -vertiss-
Advise	Latin -visare
Apprise, comprise, emprise, enterprise, prise, reprise, surprise	Latin -pre[he]ndere French -pris-
Arise, rise	Old English risan
Chastise	[No evidence of an -is- form]
Circumcise, excise, incise	Latin -cidere (supine -cisum)
Compromise, demise, premise, promise, surmise	Latin -mittere (supine -missum)
Despise	Latin despicere French despis-
Devise, improvise, supervise, televise	Latin -videre (supine -visum)
Disenfranchise, enfranchise, franchise	Old French franchise
Disguise, guise	Old French guise
Exercise	Latin exarcere Old French exercice
Merchandise	Old French marchandise
Wise	Old English wise

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