RADICAL.

Synonyms:

complete,ingrained,perfect,
constitutional,innate,positive,
entire,native,primitive,
essential,natural,thorough,
extreme,organic,thoroughgoing,
fundamental,original,total.

The widely divergent senses in which the word radical is used,[300] by which it can be at some time interchanged with any word in the above list, are all formed upon the one primary sense of having to do with or proceeding from the root (L. radix); a radical difference is one that springs from the root, and is thus constitutional, essential, fundamental, organic, original; a radical change is one that does not stop at the surface, but reaches down to the very root, and is entire, thorough, total; since the majority find superficial treatment of any matter the easiest and most comfortable, radical measures, which strike at the root of evil or need, are apt to be looked upon as extreme.

Antonyms:

conservative,incomplete,palliative,slight,tentative,
inadequate,moderate,partial,superficial,trial.

RARE.

Synonyms:

curious,odd,scarce,unique,
extraordinary,peculiar,singular,unparalleled,
incomparable,precious,strange,unprecedented,
infrequent,remarkable,uncommon,unusual.