Definition of "radical" in 英语

adjective

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

   • His beliefs are radical.

2. (botany, not comparable) Pertaining to a root (of a plant).

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

4. Thoroughgoing; far-reaching.

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

5. (lexicography, not comparable) Of or pertaining to the root of a word.

6. (phonology, phonetics, not comparable, of a sound) Produced using the root of the tongue.

7. (chemistry, not comparable) Involving free radicals.

8. (mathematics) Relating to a radix or mathematical root.

   • a radical quantity; a radical sign

9. (slang) Excellent; awesome.

   • That was a radical jump!

noun

1. (historical, 19th-century Britain, politics) A member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).

2. (historical, early 20th-century France) A member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.

3. A person with radical opinions.

4. (arithmetic) A root (of a number or quantity).

5. (linguistics) In 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 phonetic.

6. (linguistics) In Celtic languages, the basic, underlying form of an initial consonant which can be further mutated under the Celtic initial consonant mutations.

7. (linguistics) In Semitic languages, any one of the set of consonants (typically three) that make up a root.

8. (chemistry) A group of atoms, joined by covalent bonds, that take part in reactions as a single unit.

9. (organic chemistry) A free radical.

10. (algebra, commutative algebra, ring theory, of an ideal) Given an ideal I in a commutative ring R, another ideal, denoted Rad(I) or √, 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.

11. (algebra, ring theory, of a ring) Given a ring R, an ideal containing elements of R that share a property considered, in some sense, "not good".

12. (algebra, ring theory, of a module) The intersection of maximal submodules of a given module.