adjective / noun
radical
RAD-ih-kuhl/ˈrædɪkl/
Departing substantially from established practices.
The advocate proposes a radical change: replacing royal rule with voting.

Etymology
Something radical concerns the “root,” hence the origin or essentials of a thing. Applied to reform, this became change “from the roots”: altering a system fundamentally rather than adjusting its surface.
In context
calling for radical social and political change
More examples
- Working from home requires a radical shift in our routines.
- The radicals demand an entirely new system of government.
- That skateboard trick is radical!
Forms
radical · radicals · more radical · most radical
radically adverb — In a way that changes basic features.
radicalism noun — Support for fundamental political or social change.
Similar words
- revolutionary
- Suggests overturning an existing system, not merely changing its practices.
- sweeping
- Emphasizes how widely changes apply rather than their fundamental nature.
- unconventional
- Departs from usual practices without necessarily seeking fundamental change.