1
a
: very new and different from what is traditional or ordinary
The computer has introduced radical innovations.
radical ideas about education
b
: very basic and important
There are some radical differences between the two proposals.
The new president has made some radical changes to the company.
radical reforms
2
: having extreme political or social views that are not shared by most people
radical liberals/conservatives
a radical wing of extremists
3
US slang, somewhat old-fashioned
: very appealing or good
The party was totally radical! [=cool]
plural radicals
: a person who favors extreme changes in government : a person who has radical political opinions
He was a radical when he was young, but now he's much more moderate.
Cite this Entry
“Radical.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/radical. Accessed 3 Jun. 2026.
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