radical

1 being very far from the center of public opinion the baggy trousers that Amelia Bloomer introduced in the 1850s were considered a radical form of dress for women at the time Synonyms extremist, fanatic (or fanatical), rabid, extreme, revolutionary, revolutionist, ultraRelated Words subversive, violent, wild; reactionaryNear Antonyms conservative, moderate, temperate; conventional, orthodox, traditional; liberal, progressiveAntonyms middle-of-the-road, nonrevolutionary, unrevolutionary

2 not bound by traditional ways or beliefs radical proponents of spelling reform would have every word spelled “just the way it sounds” Synonyms broad-minded, nonconventional, nonorthodox, nontraditional, open-minded, progressive, liberal, unconventional, unorthodoxRelated Words advanced, contemporary, modern; forbearing, indulgent, large-minded, lenient, permissive, tolerant; extreme; impartial, objective, unbiasedNear Antonyms hard, rigid, strict; doctrinal, dogmatic (also dogmatical); bigoted, blinkered, intolerant, narrow-minded; reactionary, unreconstructedAntonyms conservative, conventional, hidebound, nonprogressive, old-fashioned, orthodox, stodgy, traditional

3 slang  of the very best kind surfing conditions at virtually all of the beaches along the coast were truly radical Synonyms A-OK, A1, awesome, bang-up, banner, beautiful, blue-chip, blue-ribbon, boffo, bonny (also bonnie) [chiefly British], boss [slang], brag, brave, bully, bumper, capital, choice, classic, cool [slang], corking, crackerjack, cracking, dandy, divine, dope [slang], down [slang], dynamite, fab, fabulous, famous, fantabulous [slang], fantastic, fine, first-class, first-rate, first-string, five-star, four-star, frontline, gangbusters (also gangbuster), gilt-edged (or gilt-edge), gone [slang], grand, great, groovy, heavenly, high-class, hot, hype [slang], immense, jim-dandy, keen, lovely, marvelous (or marvellous), mean, neat, nifty, noble, number one (also No. 1), numero uno, out-of-sight [slang], par excellence, peachy, peachy keen, phat [slang], prime, primo [slang], prize, prizewinning, quality, excellent [slang], righteous [slang], sensational, slick, splendid, stellar, sterling, superb, superior, superlative, supernal, swell, terrific, tip-top, top, top-flight, top-notch, top-of-the-line, topping [chiefly British], top-shelf, unsurpassed, wizard [chiefly British], wonderfulRelated Words acceptable, adequate, all right, decent, good, OK (or okay), passable, satisfactory, tolerable; better, exceptional, fancy, high-grade, high-test, premium, select, special, superfine; classical, standard, traditionalNear Antonyms bad, inferior, low-grade, substandard, unsatisfactory; mediocre, middling, second-class, second-rateAntonyms atrocious, awful, execrable, lousy, pathetic, poor, rotten, terrible, vile, wretched

a person who favors rapid and sweeping changes especially in laws and methods of government radicals staged large, violent protests in the hopes of toppling the government Synonyms crazy, extremist, revolutionary, revolutionist Related Words young Turk; leftist, lefty, red; progressive, reformer, reformist; anarch, anarchist, subversive; agitator, insurgent, insurrectionist, rebel; secessionist, separationist, separatist Near Antonyms conservative, fuddy-duddy, reactionary, rightist, standpatter, Tory, traditionalist Antonyms middle-of-the-roader, moderate