deputize v.

c. 1400, "subordinate officer, one given the full power of an officer without holding the office," from Anglo-French deputé, noun use of past-participle of Old French députer "appoint, assign" (14c.), from Late Latin deputare "to destine, allot," in classical Latin "to esteem, consider, consider as," literally "to cut off, prune," from de- "away" (see de-) + putare "to think, count, consider," literally "to cut, prune," from PIE root *pau- (2) "to cut, strike, stamp."

Meaning "person appointed or elected to act in the place of another or others" is from 1769.

word-forming element 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.