- the principles, desires, or practices of political radicals
- a radical movement, esp in politics
WordReference Random House Unabridged Dictionary of American English © 2026
rad•i•cal•ism
(rad′i kə liz′əm),USA pronunciation n.
- Governmentthe holding or following of radical or extreme views or principles.
- Governmentthe principles or practices of radicals.
- radical + -ism 1810–20
Collins Concise English Dictionary © HarperCollins Publishers::
radicalism /ˈrædɪkəˌlɪzəm/ n
rad•i•cal /ˈrædɪkəl/USA pronunciation
adj.
n. [countable]
rad•i•cal•ly, adv.
WordReference Random House Unabridged Dictionary of American English © 2026- thoroughgoing, complete, or extreme:a radical change in policy.
- Governmentfavoring drastic or extreme political, economic, or social reforms:radical politics.
- basic;
fundamental:[usually: before a noun]radical defects of character. - Slang Termsgreat;
marvelous;
wonderful:a radical dude.
n. [countable]
- a person who holds or follows extreme convictions, beliefs, or principles;
extremist. - Mathematics
- a quantity expressed as a root of another quantity.
- radical sign.
- Chemistrya group of atoms that act together as a unit.
- Linguistics(in Chinese writing) one of 214 elements that have meaning or sense, and are used with elements representing sounds to form thousands of different characters.
rad•i•cal•ly, adv.
rad•i•cal
(rad′i kəl),USA pronunciation adj.
n.
rad′i•cal•ness, n.
- of or going to the root or origin;
fundamental:a radical difference. - thoroughgoing or extreme, esp. as regards change from accepted or traditional forms:a radical change in the policy of a company.
- Governmentfavoring drastic political, economic, or social reforms:radical ideas; radical and anarchistic ideologues.
- forming a basis or foundation.
- existing inherently in a thing or person:radical defects of character.
- Mathematics
- pertaining to or forming a root.
- denoting or pertaining to the radical sign.
- irrational (def. 5b).
- Grammarof or pertaining to a root.
- Botanyof or arising from the root or the base of the stem.
n.
- a person who holds or follows strong convictions or extreme principles;
extremist. - Governmenta person who advocates fundamental political, economic, and social reforms by direct and often uncompromising methods.
- Mathematics
- 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.
- See radical sign.
- Chemistry
- group (def. 3).
- See free radical.
- Grammarroot (def. 11).
- Linguistics(in Chinese writing) one of 214 ideographic elements used in combination with phonetics to form thousands of different characters.
- Late Latin rādīcālis having roots, equivalent. to Latin rādīc- (stem of rādīx) root1 + -ālis -al1
- Middle English 1350–1400
- 1. basic, essential; original, innate, ingrained. 2. complete, unqualified, thorough; drastic, excessive, immoderate, violent. Radical, extreme, fanatical denote that which goes beyond moderation or even to excess in opinion, belief, action, etc. Radical emphasizes the idea of going to the root of a matter, and this often seems immoderate in its thoroughness or completeness:radical ideas; radical changes or reforms.Extreme applies to excessively biased ideas, intemperate conduct, or repressive legislation:to use extreme measures.Fanatical is applied to a person who has extravagant views, esp. in matters of religion or morality, which render that person incapable of sound judgments; and excessive zeal which leads him or her to take violent action against those who have differing views:fanatical in persecuting others.
- 1. 2. superficial.
'radicalism' also found in these entries (note: many are not synonyms or translations):