Origin and history of italicize

"type of printing with lines sloping to the right," 1610s, from Latin italicus "Italian, of Italy," from Italia (see Italy). So called because it was introduced in 1501 by Aldus Manutius, printer of Venice (who also gave his name to Aldine), and first used in his edition of Virgil, which was dedicated to Italy. As a noun, "italic type," 1670s.

[Italics] pull up the reader and tell him not to read heedlessly on, or he will miss some peculiarity in the italicized word. [Fowler]

Earlier (1570s) the word was used in English for the plain, sloping style of handwriting (opposed to gothic), and italic printing sometimes in English was called cursive (and also Aldine). Often, but not always, for emphasis; in manuscripts indicated by an underscored line. Related: Italics.

The Italic words in the Old and New Testament are those, which have no corresponding words in the original Hebrew or Greek; but are added by the translators, to complete or explain the sense. [Joseph Robertson, "An Essay on Punctuation," 1785]

word-forming element of Greek origin used to make verbs, Middle English -isen, from Old French -iser/-izer, from Late Latin -izare, from Greek -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached.

The variation of -ize and -ise began in Old French and Middle English, perhaps aided by a few words (such as surprise, see below) where the ending is French or Latin, not Greek. With the classical revival, English partially reverted to the correct Greek -z- spelling from late 16c. But the 1694 edition of the authoritative French Academy dictionary standardized the spellings as -s-, which influenced English.

In Britain, despite the opposition to it (at least formerly) of OED, Encyclopaedia Britannica, the Times of London, and Fowler, -ise remains dominant. Fowler thinks this is to avoid the difficulty of remembering the short list of common words not from Greek which must be spelled with an -s- (such as advertise, devise, surprise). American English has always favored -ize. The spelling variation involves about 200 English verbs.