spiritualize v.

c. 1300, "of or concerning the spirit" (especially in religious aspects), from Old French spirituel, esperituel (12c.) or directly from a Medieval Latin ecclesiastical use of Latin spiritualis "of or pertaining to breath, breathing, wind, or air; pertaining to spirit," from spiritus "of breathing, of the spirit" (see spirit (n.)). Meaning "of or concerning the church" is attested from mid-14c. Related: Spiritually. An Old English word for "spiritual" was godcundlic.

In avibus intellige studia spiritualia, in animalibus exercitia corporalia [Richard of St. Victoror (1110-1173): "Watch birds to understand how spiritual things move, animals to understand physical motion." - E.P.]

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.