Antonyms for radical

deviating by extremes:

peaceful, obedient.

fundamental, basic:

extrinsic, nonessential, unimportant, inessential, minor, unnatural, superficial, conservative, secondary, moderate.

noun:

mediocre, dogmatic, low-grade, awful, incident, slight, poor, palliative, strict, hidebound, incidental, lousy, nonprogressive, atrocious, unreconstructed, tentative, wretched, partial, hard, pathetic, inadequate, vile, inferior, conventional, execrable, second-rate, progressive, unsatisfactory, liberal, old, trial, doctrinal, middling, superficial, bad, stodgy, incomplete, terrible, rigid, substandard, old fashioned, rotten.