Radical

Radical (from Latin: radix, root) may refer to:

Politics and ideology

Classical radicalism, the ideology and movement started in late 18th century Britain and spread to continental Europe and Latin America in the 19th century
Radical politics, the political intent of fundamental societal change
Radical Party (disambiguation), several political parties
Radicals (UK), a British and Irish grouping in the early to mid-19th century
Radicalization
Politicians from the Radical Civic Union

Radical chic, a term coined by Tom Wolfe to describe the pretentious adoption of radical causes
Radical feminism, a perspective within feminism that focuses on patriarchy
Radical Islam, or Islamic extremism
Radical Christianity
Radical veganism, a radical interpretation of veganism, usually combined with anarchism
Radical Reformation, an Anabaptist movement concurrent with the Protestant Reformation

Radical (chemistry), an atom, molecule, or ion with unpaired valence electron(s)
Radical surgery, where diseased tissue or lymph nodes are removed from a diseased organ

Radical expression involving roots, also known as an nth root
- Solution in radicals
Radical symbol (√), used to indicate the square root and other roots
Radical of an algebraic group, a concept in algebraic group theory
Radical of an ideal, an important concept in abstract algebra
Radical of a ring, an ideal of "bad" elements of a ring
- Jacobson radical, consisting of those elements in a ring R that annihilate all simple right R-modules
- Nilradical of a ring, a nilpotent ideal which is as large as possible
Radical of a module, a component in the theory of structure and classification
Radical of an integer, in number theory, the product of the primes which divide an integer
Radical of a Lie algebra, a concept in Lie theory
- Nilradical of a Lie algebra, a nilpotent ideal which is as large as possible
Left (or right) radical of a bilinear form, the subspace of all vectors left (or right) orthogonal to every vector