radical

1 of 2

adjective

rad·​i·​cal ˈra-di-kəl 

1

: of, relating to, or proceeding from a root: such as

a(1)

: of or growing from the root of a plant

radical tubers

(2)

: growing from the base of a stem, from a rootlike stem, or from a stem that does not rise above the ground

radical leaves

b

: of, relating to, or constituting a linguistic root

c

: of or relating to a mathematical root

d

: designed to remove the root of a disease or all diseased and potentially diseased tissue

radical surgery

radical mastectomy

2

: of or relating to the origin : fundamental

3

a

: very different from the usual or traditional : extreme

b

: favoring extreme changes in existing views, habits, conditions, or institutions

c

: associated with political views, practices, and policies of extreme change

d

: advocating extreme measures to retain or restore a political state of affairs

the radical right

4

slang : excellent, cool

radicalness noun

radical

2 of 2

noun

1

a

: a root part

b

: a basic principle : foundation

2

a

: root sense 6

b

: a sound or letter belonging to a radical

3

: one who is radical

4

: free radical

also : a group of atoms bonded together that is considered an entity in various kinds of reactions or as a subunit of a larger molecule

5

a

: a mathematical expression indicating a root by means of a radical sign

b

: radical sign

Synonyms

Adjective

• extreme
• extremist
• fanatic
• fanatical
• rabid
• revolutionary
• revolutionist
• ultra

Noun

• crazy
• extremist
• revolutionary
• revolutionist

Examples of radical in a Sentence

Adjective

The computer has introduced radical innovations.

There are some radical differences between the two proposals.

The new president has made some radical changes to the company.

a radical wing of extremists

Noun

He was a radical when he was young, but now he's much more moderate.

radicals staged large, violent protests in the hopes of toppling the government

Recent Examples on the Web

Adjective

Everything that was radical and interesting was going on, except inside the Royal Academy of Dramatic Art, which was very old-fashioned, quite stale in its approach to things. —Sarah Larson, The New Yorker, 8 Dec. 2024

Kedar said that despite their radical roots, the opening indications were positive. —Mick Krever, CNN, 8 Dec. 2024

Noun

Obama ended up funding and arming the Syrian opposition so feebly it was slaughtered and – when its extremists joined up with radicals from Iraq’s long-running insurgency against the US occupation – metastasized into ISIS. —Nick Paton Walsh, CNN, 7 Dec. 2024

But that’s pretty typical of these radicals lying and gaslighting to scare voters into voting for them. —Armstrong Williams, Baltimore Sun, 2 Nov. 2024

Word History

Etymology

Adjective

Middle English, from Late Latin radicalis, from Latin radic-, radix root — more at root

First Known Use

Adjective

14th century, in the meaning defined at sense 1

Noun

1641, in the meaning defined at sense 1a

Phrases Containing radical

• anti-radical
• free radical
• radical chic
• radical sign
• trans exclusionary radical feminism
• trans exclusionary radical feminist

Kids Definition

radical

1 of 2 adjective

rad·​i·​cal ˈrad-i-kəl 

1

: of, relating to, or proceeding from a root

2

a

: departing sharply from the usual or ordinary : extreme

b

: of or relating to radicals in politics

radically

-k(ə-)lē

adverb

radicalness noun

radical

2 of 2 noun

1

: root entry 1 sense 5

2

: a person who favors rapid and sweeping changes especially in laws and methods of government

3

: a group of atoms bonded together that is considered as a unit in various kinds of reactions

4

a

: a mathematical expression (as √͞ x) involving a radical sign

b

: radical sign

Etymology

Adjective

Middle English radical "relating to a root," from Latin radicalis (same meaning), from earlier radic-, radix "root" — related to eradicate, radish

Word Origin

Our word radical was formed from the Latin adjective radicalis, which simply meant "of or relating to a root." The Latin word radix meant "root." This meaning was kept when the word radicalis came into English as radical, but new senses developed too. Since a root is at the bottom of something, radical came to describe what is at the base or beginning, in other words, what is "basic, fundamental." Later, radical was used to describe something that was extremely different from the usual. Then, as a noun radical came to be applied to a person who wants to make extreme or "radical" changes in the government or in society. In mathematics, a radical sign indicates a root of a number. The words radish and eradicate also come from the Latin radix.

Medical Definition

radical

1 of 2 adjective

rad·​i·​cal ˈrad-i-kəl 

1

: designed to remove the root of a disease or all diseased tissue

radical surgery

2

: involving complete removal of an organ

radical prostatectomy

compare conservative

radically

-i-k(ə-)lē 

adverb

radical

2 of 2 noun

: free radical

also : a group of atoms bonded together that is considered an entity in various kinds of reactions