# radical

/ˈɹædəkəɫ/ (US) · /ɹˈædɪkəl/ (UK)

Source: https://englishreference.com/word/radical
Updated: 2026-06-19

## Senses

### 1. extreme or fundamental

adjective · CEFR B2

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

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

- The company needs a radical change in how it treats its customers.
- The new CEO proposed a radical restructuring of the entire organization to eliminate redundant management layers.

### 2. politically extreme

adjective · CEFR C1 · Academic

supporting complete social or political change.

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

- He joined a radical political group while he was at university.
- The manifesto outlined a radical vision for wealth redistribution that alienated the more moderate members of the party.

### 4. a person with extreme views

noun · CEFR C1 · Formal

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

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

- In the 1960s, many students were seen as radicals by the government.
- The historian argued that the radicals of the nineteenth century paved the way for modern democratic institutions.

### 5. chemistry/science

noun · CEFR C2 · Technical

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

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

- Antioxidants help protect your body from damage caused by free radicals.
- The researcher monitored the formation of short-lived radicals during the combustion process using high-speed spectroscopy.

### 6. Chinese character component

noun · CEFR C1 · Technical

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

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

- The radical for 'water' appears on the left side of many characters related to liquid.
- Students of Mandarin often find that memorizing the 214 traditional radicals significantly accelerates their ability to recognize complex characters.

### 7. mathematics

noun · CEFR C2 · Technical

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

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

- You need to simplify the expression under the radical.
- The equation requires the extraction of a cubic radical to find the value of the unknown variable.

## Examples

- He became a radical after seeing how the poor were treated.
- The university was known as a meeting place for radicals who wanted to overthrow the existing government.
- While the moderates were willing to negotiate for minor policy shifts, the radicals insisted that only a complete overhaul of the constitution would satisfy the public's demands.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.