radical
Noun pluralradicals
Pluralradicals
- 1Having very extreme ideas about politics or religion, and sometimes ready to support violence.
The young man was pulled into a radical group he found online.
Police are keeping watch on a radical preacher who praises attacks.
UsageIn this meaning, it is a strong word that shows disapproval.
Similarextremist, militant, fanatical, hardline
Oppositemoderate
Note
- 2Very great and basic, changing or touching the most important parts of something.
Like turning a whole house upside down, not just moving one chair.
The company made radical changes to how it pays its workers.
Doctors warned that only a radical shift in lifestyle would help.
UsageOften in radical change.
Similarfundamental, thorough, sweeping, drastic, far-reaching
Oppositesuperficial, minor, cosmetic, slight
Note
- 3Wanting big, deep changes that fix the root cause of a problem, not just the surface.
Like pulling a weed out by its roots instead of just cutting off the top.
She holds radical views on how schools should be run.
Her radical views focus on the causes of poverty, not its symptoms.
UsageThe opposite is moderate.
Similarrevolutionary, drastic, sweeping, fundamental, extreme
Oppositemoderate, conservative, gradual, incremental
Note
- 4Very new and daring, and very different from what people usually do or accept.
The architect's radical design for the museum shocked the whole city.
Her radical new haircut surprised everyone at school.
UsageCan be praise or criticism.
Similarrevolutionary, innovative, unconventional, bold, daring
Oppositeconventional, traditional, conservative
Note
- 5A particle with a spare, unpaired electron that is usually very reactive and can damage other molecules.
Like a magnet missing one piece, grabbing onto anything nearby.
Too much sunlight can create radicals that damage skin cells.
Smoking creates free radicals that can damage the cells in your body.
UsageMost people say free radical.
Note
- 6Someone who wants big, deep changes to society or government.
Like someone who wants to tear down the old building and start fresh, not just fix the windows.
The young radical demanded an end to all the old rules.
As a radical, he refused to settle for small fixes.
UsageWith a capital R, it can mean a member of a particular political party or group.
Similarextremist, revolutionary, militant, firebrand, zealot
Oppositemoderate, conservative
- 7Having to do with free radicals, the very reactive particles studied in chemistry.
The plastic forms through a radical reaction.
Sunlight can start a radical process in the air.
Note
- 8The part of a Chinese character used to find it in a dictionary, which often hints at its meaning.
Like a small picture clue inside a word that hints what it means.
The water radical appears in many characters about rivers, lakes, and seas.
The water radical tells you a character probably has to do with liquid.
Note
- 9A member of a political group called the Radicals, in Britain or France, that wanted reform.
Like the boldest members of a group who want big changes but not to change everything.
My great-great-grandfather was elected to Parliament as a Radical.
The small French town has elected a Radical as mayor for decades.
UsageWritten with a capital R; it does not mean extremist here.
Note
Less common meanings
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- 11
- 12A group of atoms that stay joined and act together as one unit in chemical reactions.
Like a team that travels from game to game together, never splitting up.
The sulfate radical stays together as the compound dissolves.
Chemists once called ammonium a radical because its atoms act as one unit.
Similargroup
Note
- 13Having to do with the root of a number, or the √ sign used to show it.
The radical sign tells you to find a root.
She wrote the answer in radical form.
Note
- 14Relating to the root part of a word, the base that other forms grow from.
Like the seed a plant grows from, with the rest of the word growing around it.
The radical part of a word stays the same when you add endings.
Students learned to find the radical element in each long word.
Note
- 15In Semitic languages such as Arabic, one of the consonants, usually three, that form a word's root.
Like the frame of a house, with vowels added on like the walls.
Each radical in the word is a single consonant.
The three radicals together carry the basic meaning.
Note
- 16Growing from the root or the base of a plant, close to the ground.
Like leaves that sprout straight from the ground instead of from a tall stem.
The plant's radical leaves spread flat against the soil.
A primrose has radical leaves that form a flat circle near the ground.
Similarbasal
Note
- 17In math, the number you get by multiplying together the different prime factors of a whole number.
Like keeping just one of each kind of building block, even if a number uses several copies.
The radical of 12 is 6, because its prime factors are 2 and 3.
We found the radical by multiplying each different prime factor once.
Note
- 18In speech, a sound made using the back base of the tongue near the throat.
Like making a sound from way back in your throat instead of with your lips.
Some Arabic sounds are radical, made deep in the throat.
A radical sound is made far back, near the throat.
Note
- 19In Celtic languages, the basic form of a word's first consonant before any sound changes alter it.
Like a word's plain starting sound before grammar changes it.
In Irish, the radical appears when no mutation is triggered.
In Welsh, the radical c in "cath" can change to g.
Note
- 20In advanced math, a special part of a ring, ideal, or module made from certain elements.
The radical of an ideal always contains the original ideal.
Any element with some power in the ideal belongs to its radical.
Note
Showing meanings only.
Practice
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Origin
It came through Middle English from Latin rādīcālis, meaning 'of or relating to the root.'
Checked 1 Nov 2026 · 2 facts
- Radical came through Middle English from Latin rādīcālis. en.wiktionary.org
- Latin rādīcālis means 'of or relating to the root.' en.wiktionary.org