signalize v.

late 14c., "visible sign, indication" (a sense now obsolete), also "a supernatural act of God; a device on a banner," from Old French signal, seignal "seal, imprint, sign, mark," from Medieval Latin signale "a signal," from Late Latin signalis (adj.) "used as a signal, pertaining to a sign," from Latin signum "identifying mark, sign" (see sign (n.)).

The restricted sense of "conventional or agreed-upon sign" (to commence or desist, etc.) is from 1590s. The meaning "modulation of an electric current" is from 1855, later applied to electromagnetic waves, hence the use of signal in radio (later television) broadcasting (1923). The railroad signalman is attested by 1840.

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.

1805, "make signals to," from signal (n.). Related: Signaled; signaler; signaling. The earlier verb was signalize.