radicalize (v.)

late 14c., "originating in the root or ground;" of body parts or fluids, "vital to life," from Latin radicalis "of or having roots," from Latin radix (genitive radicis) "root" (from PIE root *wrād- "branch, root"). The basic sense of the word in all meanings is "pertaining or relating to a root or roots," hence "thoroughgoing, extreme."

The figurative meaning "going to the origin, essential" is from 1650s. The political sense of "reformist" is by 1817, of the extreme section of the British Liberal party (radical reform had been a current phrase since 1786), via the notion of "change from the roots" (see radical (n.)). The meaning "unconventional" is from 1921. U.S. youth slang use is from 1983, from 1970s surfer slang meaning "at the limits of control."

The mathematical radical sign, placed before any quantity to denote that its root is to be extracted, is from 1680s; the sign itself is a modification of the letter -r-. Radical chic is attested from 1970; popularized, if not coined, by Tom Wolfe. Radical empiricism was coined 1897 by William James (see empiricism).

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.