RADICAL

Pronunciation (US):

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IPA (US):

 Dictionary entry overview: What does radical mean? 

• RADICAL (noun)
  The noun RADICAL has 6 senses:

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

2. 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

3. a person who has radical ideas or opinions

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

5. a character conveying the lexical meaning of a logogram

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

  Familiarity information: RADICAL used as a noun is common.

• RADICAL (adjective)
  The adjective RADICAL has 5 senses:

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

2. markedly new or introducing radical change

3. arising from or going to the root or source

4. of or relating to or constituting a linguistic root

5. 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

  Familiarity information: RADICAL used as an adjective is common.

 Dictionary entry details 

• RADICAL (noun)

Sense 1

Meaning:

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

Classified under:

Nouns denoting substances

Synonyms:

chemical group; group; radical

Hypernyms ("radical" is a kind of...):

building block; unit (a single undivided natural thing occurring in the composition of something else)

Domain category:

chemical science; chemistry (the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions)

Hyponyms (each of the following is a kind of "radical"):

carboxyl; carboxyl group (the univalent radical -COOH; present in and characteristic of organic acids)

vinyl; vinyl group; vinyl radical (a univalent chemical radical derived from ethylene)

chromophore (the chemical group that gives color to a molecule)

cyanide group; cyanide radical; cyano group; cyano radical (the monovalent group -CN in a chemical compound)

glyceryl (a trivalent radical derived from glycerol by removing the three hydroxyl radicals)

hydrazo group; hydrazo radical (the bivalent group -HNNH- derived from hydrazine)

hydroxyl; hydroxyl group; hydroxyl radical (the monovalent group -OH in such compounds as bases and some acids and alcohols)

ketone group (a group having the characteristic properties of ketones)

methylene; methylene group; methylene radical (the bivalent radical CH2 derived from methane)

propyl; propyl group; propyl radical (the monovalent organic group C3H7- obtained from propane)

butyl (a hydrocarbon radical (C4H9))

nitro group (the group -NO3)

nitrite (the radical -NO2 or any compound containing it (such as a salt or ester of nitrous acid))

uranyl; uranyl group; uranyl radical (the bivalent radical UO2 which forms salts with acids)

carbonyl group (the bivalent radical CO)

arsenic group; cacodyl; cacodyl group; cacodyl radical (the univalent group derived from arsine)

benzoyl group; benzoyl radical (the univalent radical derived from benzoic acid)

benzyl; benzyl group; benzyl radical (the univalent radical derived from toluene)

azo group; azo radical (the bivalent group -N=N- united to two hydrocarbon groups)

azido group; azido radical (the univalent group N3- derived from hydrazoic acid)

amyl (a hydrocarbon radical that occurs in many organic compounds)

amino; amino group (the radical -NH2)

allyl; allyl group; allyl radical (the univalent unsaturated organic radical C3H5; derived from propylene)

alkyl; alkyl group; alkyl radical (any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons)

aldehyde group; aldehyde radical (the chemical group -CHO)

alcohol group; alcohol radical (the chemical group -OH)

acyl; acyl group (any group or radical of the form RCO- where R is an organic group)

Holonyms ("radical" is a part of...):

molecule ((physics and chemistry) the simplest structural unit of an element or compound)

Sense 2

Meaning:

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

Classified under:

Nouns denoting substances

Synonyms:

free radical; radical

Context example:

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

Hypernyms ("radical" is a kind of...):

atom ((physics and chemistry) the smallest component of an element having the chemical properties of the element)

Sense 3

Meaning:

A person who has radical ideas or opinions

Classified under:

Nouns denoting people

Hypernyms ("radical" is a kind of...):

individual; mortal; person; somebody; someone; soul (a human being)

Hyponyms (each of the following is a kind of "radical"):

anarchist; nihilist; syndicalist (an advocate of anarchism)

young Turk (a young radical who agitates for reform)

Wobbly (a member of the Industrial Workers of the World)

Trot; Trotskyist; Trotskyite (radicals who support Trotsky's theory that socialism must be established throughout the world by continuing revolution)

terrorist (a radical who employs terror as a political weapon; usually organizes with other terrorists in small cells; often uses religion as a cover for terrorist activities)

revolutionary; revolutionist; subversive; subverter (a radical supporter of political or social revolution)

leveler; leveller (a radical who advocates the abolition of social distinctions)

extremist (a person who holds extreme views)

Bolshevik; bolshie; bolshy; Marxist; red (emotionally charged terms used to refer to extreme radicals or revolutionaries)

Sense 4

Meaning:

(mathematics) a quantity expressed as the root of another quantity

Classified under:

Nouns denoting quantities and units of measure

Hypernyms ("radical" is a kind of...):

amount; measure; quantity (how much there is or how many there are of something that you can quantify)

Domain category:

math; mathematics; maths (a science (or group of related sciences) dealing with the logic of quantity and shape and arrangement)

Sense 5

Meaning:

A character conveying the lexical meaning of a logogram

Classified under:

Nouns denoting communicative processes and contents

Hypernyms ("radical" is a kind of...):

character; graph; grapheme; graphic symbol (a written symbol that is used to represent speech)

Holonyms ("radical" is a part of...):

ideogram; ideograph (a graphic character that indicates the meaning of a thing without indicating the sounds used to say it)

Sense 6

Meaning:

(linguistics) the form of a word after all affixes are removed

Classified under:

Nouns denoting communicative processes and contents

Synonyms:

base; radical; root; root word; stem; theme

Context example:

thematic vowels are part of the stem

Hypernyms ("radical" is a kind of...):

descriptor; form; signifier; word form (the phonological or orthographic sound or appearance of a word that can be used to describe or identify something)

Domain category:

linguistics (the scientific study of language)

• RADICAL (adjective)

Sense 1

Meaning:

(used of opinions and actions) far beyond the norm

Synonyms:

extremist; radical; ultra

Context example:

an ultra conservative

Similar:

immoderate (beyond reasonable limits)

Sense 2

Meaning:

Markedly new or introducing radical change

Synonyms:

radical; revolutionary

Context example:

radical political views

Similar:

new (not of long duration; having just (or relatively recently) come into being or been made or acquired or discovered)

Sense 3

Meaning:

Arising from or going to the root or source

Context example:

a radical flaw in the plan

Similar:

basic (pertaining to or constituting a base or basis)

Sense 4

Meaning:

Of or relating to or constituting a linguistic root

Classified under:

Relational adjectives (pertainyms)

Context example:

a radical verb form

Domain category:

linguistics (the scientific study of language)

Pertainym:

root ((linguistics) the form of a word after all affixes are removed)

Sense 5

Meaning:

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

Synonyms:

basal; radical

Context example:

radical leaves

Domain category:

botany; phytology (the branch of biology that studies plants)

Antonym:

cauline (especially of leaves; growing on a stem especially on the upper part of a stem)

 Context examples 

Mice treated with SFN showed increased expression of antioxidant markers, decreased free radical cell damage and had significantly improved cognitive ability in memory tasks.

(Antioxidants May Prevent Cognitive Impairment in Diabetes, The Titi Tudorancea Bulletin)

Eclipses are the most radical tool the universe uses to create change.

(AstrologyZone.com, by Susan Miller)

The vast majority of cases recur if they are not treated with radical surgery.

(Adamantinoma of Long Bones, NCI Thesaurus)

The researchers tested the strength of the flies’ antioxidant defenses against toxic versions of several chemicals found in cells called oxygen free radicals.

(NIH scientists search for the clocks behind aging brain disorders, National Institutes of Health)

Azelaic acid also possesses a direct anti-inflammatory effect due to its scavenger activity of free oxygen radical.

(Azelaic Acid, NCI Thesaurus)

For a moment it seemed to me that there must be some radical mistake in my calculations.

(The Memoirs of Sherlock Holmes, by Sir Arthur Conan Doyle)

In addition, mesalamine may act as a scavenger of reactive oxygen free radicals.

(Olsalazine, NCI Thesaurus)

But the most radical change of all, and the one that pleased her most, was the change in his speech.

(Martin Eden, by Jack London)

They also inhibit a variety of pro-inflammatory enzymes, such as cyclooxygenase 1 (COX-1) and COX-2, block the formation of reactive-oxygen species and neutralize free radicals.

(Olive Oil Extract/Curcumin-based Capsule, NCI Thesaurus)

It is an antioxidant that helps prevent cell damage caused by free radicals (highly reactive chemicals).

(Ascorbic acid, NCI Dictionary)