Definitions
1.noun(historical: 19th-century Britain) A member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).
2.noun(historical: early 20th-century France) A member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.
3.nounA person with radical opinions.
4.nounA root (of a number or quantity).
5.nounIn 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.nounIn Semitic languages, any one of the set of consonants (typically three) that make up a root.
7.nounA group of atoms, joined by covalent bonds, that take part in reactions as a single unit.
8.nounA free radical.
9.noun(commutative algebra, of an ideal) Given an ideal I in a commutative ring R, another ideal, denoted Rad(I) or \sqrt{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.
10.noun(of a ring) Given a ring R, an ideal containing elements of R that share a property considered, in some sense, "not good".
11.noun(of a module) The intersection of maximal submodules of a given module.
12.nounThe product of the distinct prime factors of a given positive integer.
13.adjectiveFavoring fundamental change, or change at the root cause of a matter."His beliefs are radical."
14.adjectivePertaining to a root (of a plant).
15.adjectivePertaining to the basic or intrinsic nature of something.
16.adjectiveThoroughgoing; far-reaching."The spread of the cancer required radical surgery, and the entire organ was removed."
17.adjectiveOf or pertaining to the root of a word.
18.adjective(of a sound) Produced using the root of the tongue.
19.adjectiveInvolving free radicals.
20.adjectiveRelating to a radix or mathematical root."a radical quantity; a radical sign"
21.adjective(1980s & 1990s) Excellent; awesome."That was a radical jump!"