of or going to the root or origin; fundamental: There is a radical difference between the two interpretations of the sacred text, one justifying war and the other requiring nonviolent resistance.
extreme, especially as regards change from accepted or traditional forms: a radical change in the policy of the 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.
characterized by a marked departure from prevailing methods, practices, or ideas, particularly in the arts; experimental; unorthodox: The composer’s radical approach to sound, using timbre and rhythm rather than pitch, was declared “noise” by an influential critic.
Slang. excellent; wonderful; cool; rad: You got here on an electric skateboard? That's radical!
pertaining to or forming a root.
denoting or pertaining to the radical sign.
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.
Grammar. root1 (def. 12).
(in Chinese writing) one of 214 ideographic elements used in combination with phonetics to form thousands of different characters.
Latin rādix comes from wrād-, one of the variants of the Proto-Indo-European root wrād, werād, wred- “root, branch.” From this same variant, Latin also has rāmus “branch” (the root, so to speak, of English ramify ), while Greek has rhádix (stem rhádik- ). Another variant of the root is the possible source of Greek rhiza, source of English rhizome; other variants include Aeolic briza, brisda and Mycenaean wriza. Wrād- regularly becomes wrōt- in Proto-Germanic, the ultimate source of the English word root.
- rad·i·cal·i·ty [rad-i-kal-i-tee], /ˌræd ɪˈkæl ɪ ti/, rad·i·cal·ness, noun
- mul·ti·rad·i·cal, adjective
- non·rad·i·cal, adjective, noun
- qua·si-rad·i·cal, adjective
- sem·i·rad·i·cal, adjective
- sub·rad·i·cal, adjective
- su·per·rad·i·cal, adjective
- ul·tra·rad·i·cal, adjective, noun
- un·rad·i·cal, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use radical in a sentence
Old friends who never seemed to care about politics now seem ready to rain blows on those who disagree with their radical views.Politics and conspiracy theories are fracturing relationships. Here’s how to grieve those broken bonds. | Jeff Schrum | February 11, 2021 | Washington Post
We asked them to lay out the steps for this radical classroom transformation.
An idea born in a Swiss patent office that evolved into a mature theory in Berlin set forth a radical new picture of the cosmos, rooted in a new, deeper understanding of gravity.Einstein’s theory of general relativity unveiled a dynamic and bizarre cosmos | Elizabeth Quill | February 3, 2021 | Science News
The anxiety and loss of community some Q believers may feel can make them more vulnerable to believing radical ideas.
Developing radical new technology is inherently risky, but that doesn’t make breaking this news any easier.Loon’s bubble bursts—Alphabet shuts down Internet balloon company | Ron Amadeo | January 22, 2021 | Ars Technica
But Brooke was out of step with the New Left and its notion of radical chic.Ed Brooke: The Senate's Civil Rights Pioneer and Prophet of a Post-Racial America | John Avlon | January 4, 2015 | THE DAILY BEAST
Too moderate and the more radical groups call you a snitch, jeopardizing your standing and authority at demonstrations.De Blasio and the New York City Protesters Have No Blood on Their Hands | Jacob Siegel | December 22, 2014 | THE DAILY BEAST
He has become the most radical pope in modern memory for his economic populism.
He branded it a fifth-column invasion into popular culture, normalizing radical, even communist ambitions.Glenn Beck Is Now Selling Hipster Clothes. Really. | Ana Marie Cox | December 20, 2014 | THE DAILY BEAST
Two hostages are dead and 15 others free after an Islamic radical took them hostage before police killed him.
This letter indirectly points out two long-standing radical errors in engineering phraseology.Life of Richard Trevithick, Volume II (of 2) | Francis Trevithick
Decandolle's observations regarding the radical excretions of plants have not been confirmed by subsequent observers.Elements of Agricultural Chemistry | Thomas Anderson
But if this reincarnation was quite ordinary in its process, it was the more radical and decisive.The Life & Letters of Peter Ilich Tchaikovsky | Modeste Tchaikovsky
There are two radical differences between Humanism and Christianity.God and my Neighbour | Robert Blatchford
If the Collier were a radical, how coal-black the portraits would come out!
British Dictionary definitions for radical
of, relating to, or characteristic of the basic or inherent constitution of a person or thing; fundamental: a radical fault
concerned with or tending to concentrate on fundamental aspects of a matter; searching or thoroughgoing: radical thought; a radical re-examination
favouring or tending to produce extreme or fundamental changes in political, economic, or social conditions, institutions, habits of mind, etc: a radical party
med (of treatment) aimed at removing the source of a disease: radical surgery
slang, mainly US very good; excellent
of, relating to, or arising from the root or the base of the stem of a plant: radical 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
- radicalness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for radical
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Cultural definitions for radical (1 of 2)
In politics, someone who demands substantial or extreme changes in the existing system.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.