What does "radical" mean?

1. (extreme or fundamental) describing a very big or important change that affects the basic nature of something. 2. (politically extreme) supporting complete social or political change. 3. (a person with extreme views) someone who wants to change the whole social or political system. 4. (chemistry/science) a group of atoms that usually stays together during a chemical reaction. 5. (Chinese character component) the part of a Chinese character that often shows its general meaning. 6. (mathematics) a sign used to show the root of a number, like a square root.

radical

adj. · n.

US //ˈɹædəkəɫ// UK //ɹˈædɪkəl// rad·i·cal

1 extreme or fundamental (adj.)
B2 Upper Intermediate

describing a very big or important change that affects the basic nature of something.

relating to or affecting the fundamental nature of something; far-reaching or thoroughgoing.

Example

The company needs a radical change in how it treats its customers.

Example

The new CEO proposed a radical restructuring of the entire organization to eliminate redundant management layers.
- minor
- superficial
2 politically extreme (adj.)
C1 Advanced Academic

supporting complete social or political change.

advocating for thorough or complete social and political reform from the roots up.

Example

He joined a radical political group while he was at university.

Example

The manifesto outlined a radical vision for wealth redistribution that alienated the more moderate members of the party.
- revolutionary
- extremist
- moderate
- conservative

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3 a person with extreme views (n.)
C1 Advanced Formal

someone who wants to change the whole social or political system.

a person who advocates for thorough or complete social and political reform.

Example

In the 1960s, many students were seen as radicals by the government.

Example

The historian argued that the radicals of the nineteenth century paved the way for modern democratic institutions.
- extremist
- revolutionary
- moderate
4 chemistry/science (n.)
C2 Proficiency Technical Science

a group of atoms that usually stays together during a chemical reaction.

an atom, molecule, or ion that has at least one unpaired valence electron and is often highly reactive.

Example

Antioxidants help protect your body from damage caused by free radicals.

Example

The researcher monitored the formation of short-lived radicals during the combustion process using high-speed spectroscopy.
- free radical
5 Chinese character component (n.)
C1 Advanced Technical

the part of a Chinese character that often shows its general meaning.

the graphical component of a Chinese character under which the character is traditionally listed in a dictionary.

Example

The radical for 'water' appears on the left side of many characters related to liquid.

Example

Students of Mandarin often find that memorizing the 214 traditional radicals significantly accelerates their ability to recognize complex characters.
- component
- classifier
6 mathematics (n.)
C2 Proficiency Technical Math

a sign used to show the root of a number, like a square root.

a quantity expressed as a root of another quantity; also the symbol used to denote such a root.

Example

You need to simplify the expression under the radical.

Example

The equation requires the extraction of a cubic radical to find the value of the unknown variable.
- root

Origin

PIE word *wréh₂ds Inherited from Middle English radical, from Latin rādīcālis (“of or pertaining to the root, having roots, radical”). Compare grassroots.

Word family

Nounradicalism
Adjectiveradical
Adverbradically