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English adjective: radical

1. radical (used of opinions and actions) far beyond the norm

SamplesExtremist political views.
Radical opinions on education.
An ultra conservative.

Synonymsextremist, ultra



2. radical markedly new or introducing radical change

SamplesA revolutionary discovery.
Radical political views.




3. radical arising from or going to the root or source

SamplesA radical flaw in the plan.


Antonymsincidental, incident

4. radical of or relating to or constituting a linguistic root

SamplesA radical verb form.

Domain categorylinguistics

5. radical especially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem

SamplesBasal placentation.
Radical leaves.


Domain categorybotany, phytology


English noun: radical

1. radical (substance) (chemistry) two or more atoms bound together as a single unit and forming part of a molecule

Synonymschemical group, group

Broader (hypernym)building block, unit

Narrower (hyponym)acyl, acyl group, alcohol group, alcohol radical, aldehyde group, aldehyde radical, alkyl, alkyl group, alkyl radical, allyl, allyl group, allyl radical, amino, amino group, amyl, arsenic group, azido group, azido radical, azo group, azo radical, benzoyl group, benzoyl radical, benzyl, benzyl group, benzyl radical, butyl, cacodyl, cacodyl group, cacodyl radical, carbonyl group, carboxyl, carboxyl group, chromophore, cyanide group, cyanide radical, cyano group, cyano radical, glyceryl, hydrazo group, hydrazo radical, hydroxyl, hydroxyl group, hydroxyl radical, ketone group, methylene, methylene group, methylene radical, nitrite, nitro group, propyl, propyl group, propyl radical, uranyl, uranyl group, uranyl radical, vinyl, vinyl group, vinyl radical

Part meronymmolecule

Domain categorychemical science, chemistry

2. radical (substance) an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule

SamplesIn the body free radicals are high-energy particles that ricochet wildly and damage cells.

Synonymsfree radical

Broader (hypernym)atom

3. radical (person) a person who has radical ideas or opinions

Broader (hypernym)individual, mortal, person, somebody, someone, soul

Narrower (hyponym)anarchist, Bolshevik, bolshie, bolshy, extremist, leveler, leveller, Marxist, nihilist, red, revolutionary, revolutionist, subversive, subverter, syndicalist, terrorist, Trot, Trotskyist, Trotskyite, Wobbly, young Turk

4. radical (quantity) (mathematics) a quantity expressed as the root of another quantity

Broader (hypernym)amount, measure, quantity

Domain categorymath, mathematics, maths

5. radical (communication) a character conveying the lexical meaning of a logogram

Broader (hypernym)character, grapheme, graphic symbol

Part meronymideogram, ideograph

6. radical (communication) (linguistics) the form of a word after all affixes are removed

SamplesThematic vowels are part of the stem.

Synonymsbase, root, root word, stem, theme

Broader (hypernym)descriptor, form, signifier, word form

Domain categorylinguistics

Based on WordNet 3.0 copyright © Princeton University.
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