radical

Pertaining to the basic or intrinsic nature of something.

wanting complete change in the way a country or a system works, not small steps

Thoroughgoing; far-reaching.

(slang) Excellent; awesome.

Involving free radicals.

Relating to a radix or mathematical root.

Of or pertaining to the root of a word.

Of or pertaining to the root of a plant.

Produced using the root of the tongue.

A person with radical opinions.

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

A free radical.

(historical) A member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).

(historical) A member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.

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.

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 being wholly phonetic.

(nonstandard) Any component of a logographic character, whether used for indexing or not, whether semantic or not.

A root (of a number or quantity).

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

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

The product of the distinct prime factors of a given positive integer.

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.

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

The intersection of maximal submodules of a given module.