radical

comparative more radical · superlative most radical

1. not comparablebiologyOf or pertaining to the root of a plant.
2. not comparablehuman sciencesOf or pertaining to the root of a word.
3. not comparablehuman sciencesProduced using the root of the tongue.
4. mathematicsRelating to a radix or mathematical root.

   a radical quantity; a radical sign

5. Pertaining to the basic or intrinsic nature of something.

   The most determined exertions of that authority, against them, only showed their radical independence.

   1790 November, Edmund Burke, Reflections on the Revolution in France, and on the Proceedings in Certain Societies in London Relative to that Event. […], London: […] J[ames] Dodsley, […], →OCLC

   Synonyms: fundamental · Antonyms: ignorable, trivial

6. Favoring fundamental change, or change at the root cause of a matter.

   His beliefs are radical.

7. Thoroughgoing; far-reaching.

   The spread of the cancer required radical surgery, and the entire organ was removed.

   1 more example

   Phoenix and Lubbock are both caught in severe drought, and it is going to get much worse. We may see many such [dust] storms in the decades ahead, along with species extinctions, radical disturbance of ecosystems, and intensified social conflict over land and water. Welcome to the Anthropocene, the epoch when humans have become a major geological and climatic force.

   2012 January 28, Donald Worster, “A Drier and Hotter Future”, in American Scientist, volume 100, number 1, archived from the original on 26 Jan 2012, page 70

8. not comparablechemistryInvolving free radicals.

   Synonyms: primitive

9. slangExcellent; awesome.

   That was a radical jump!

   Synonyms: rad

plural radicals

1. arithmeticA root (of a number or quantity).
2. In logographic writing systems such as the Chinese writing system, the portion of a character used to index it. Often, but not always, this is also the portion indicating meaning; compare the following sense.
   1. human sciencesIn logographic writing systems such as the Chinese writing system, the portion of a character (if any) that provides an indication of its meaning, as opposed to being wholly phonetic.

      Synonyms: semantophore

   2. commonproscribedhuman sciencesAny component of a logographic character, whether used for indexing or not, whether semantic or not.

      The boy recognised the Chinese characters, though the calligraphy looked a bit strange, as if drawn by someone who had seen them and copied them out radical by radical without knowing what they meant.

      2022, R. F. Kuang, Babel, HarperVoyager, page 9

      Synonyms: component

3. human sciencesIn Celtic languages, the basic, underlying form of an initial consonant which can be further mutated under the Celtic initial consonant mutations.
4. human sciencesIn Semitic languages, any one of the set of consonants (typically three) that make up a root.
5. chemistryA group of atoms, joined by covalent bonds, that take part in reactions as a single unit.
6. chemistryA free radical.
7. commutative algebra; ring theory; commutative algebra; ring theoryalgebraGiven an ideal I in a commutative ring R, another ideal, denoted Rad(I) or √I, such that an element x ∈ R is in Rad(I) if, for some positive integer n, xⁿ ∈ I; equivalently, the intersection of all prime ideals containing I.
8. ring theoryalgebraGiven a ring R, an ideal containing elements of R that share a property considered, in some sense, "not good".
9. ring theoryalgebraThe intersection of maximal submodules of a given module.
10. mathematicsThe product of the distinct prime factors of a given positive integer.
11. historical19th-century BritaingovernmentA member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).
12. historicalearly 20th-century FranceA member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.
13. A person with radical opinions.