- of or going to the root or origin; fundamental: a radical difference.
- thoroughgoing or extreme, especially as regards change from accepted or traditional forms: a radical change in the policy of a company.
- favoring drastic political, economic, or social reforms: radical ideas; radical and anarchistic ideologues.
- favoring, supporting, or representing extreme forms of religious fundamentalism: radical fundamentalists and their rejection of modern science.
- forming a basis or foundation: What is the radical reason for his choice?
- existing inherently in a thing or person: radical defects of character.
- Grammar. of or pertaining to the root of a word.
- Botany. of or arising from the root or the base of the stem.
- a person who holds or follows strong convictions or extreme principles; extremist.
- a person who advocates fundamental political, economic, and social reforms by direct and often uncompromising methods.
- a quantity expressed as a root of another quantity.
- the set of elements of a ring, some power of which is contained in a given ideal.
- radical sign.
- Grammar. root1(def 12).
- (in Chinese writing) one of 214 ideographic elements used in combination with phonetics to form thousands of different characters.
- of, relating to, or characteristic of the basic or inherent constitution of a person or thing; fundamentala radical fault
- concerned with or tending to concentrate on fundamental aspects of a matter; searching or thoroughgoingradical thought; a radical re-examination
- favouring or tending to produce extreme or fundamental changes in political, economic, or social conditions, institutions, habits of mind, etca radical party
- med (of treatment) aimed at removing the source of a diseaseradical surgery
- slang, mainly US very good; excellent
- of, relating to, or arising from the root or the base of the stem of a plantradical leaves
- maths of, relating to, or containing roots of numbers or quantities
- linguistics of or relating to the root of a word
- a person who favours extreme or fundamental change in existing institutions or in political, social, or economic conditions
- maths a root of a number or quantity, such as ³√5, √ x
- Also: radicle chem
- linguistics another word for root 1 (def. 9)
- (in logographic writing systems such as that used for Chinese) a part of a character conveying lexical meaning
late 14c., in a medieval philosophical sense, from Late Latin radicalis “of or having roots,” from Latin radix (genitive radicis) “root” (see radish). Meaning “going to the origin, essential” is from 1650s. Radical sign in mathematics is from 1680s.
Political sense of “reformist” (via notion of “change from the roots”) is first recorded 1802 (n.), 1817 (adj.), of the extreme section of the British Liberal party (radical reform had been a current phrase since 1786); meaning “unconventional” is from 1921. U.S. youth slang use is from 1983, from 1970s surfer slang meaning “at the limits of control.” Radical chic is attested from 1970; popularized, if not coined, by Tom Wolfe. Radical empiricism coined 1897 by William James (see empiricism).
1630s, “root part of a word, from radical (adj.) Political sense from 1802; chemical sense from 1816.
- A group of elements or atoms usually passing intact from one compound to another but generally incapable of prolonged existence in a free state.
- A free radical.
- Of or being medical treatment by extreme, drastic, or innovative measures.
- Designed to act on or eliminate the root or cause of a pathological process.
- A root, such as √2, especially as indicated by a radical sign (√).
- A group of atoms that behaves as a unit in chemical reactions and is often not stable except as part of a molecule. The hydroxyl, ethyl, and phenyl radicals are examples. Radicals are unchanged by chemical reactions.
In politics, someone who demands substantial or extreme changes in the existing system.