Other forms: radicals
Radical means going all the way down to the root. A radical rethink throws the old timetable away instead of shuffling it; radical surgery takes out everything around the problem; a radical change of diet is not swapping one biscuit for another.
In politics a radical wants deep and fast change, and the word belongs to no one side, since there are radicals on the left and the right. Radicalise is the news word for pulling a person into extreme views. The technical uses all keep the root picture: a free radical in chemistry, the radical of a Chinese character that you look the character up by, the radical sign drawn over a square root. Radical is not a polite word for dangerous, because a radical solution can be the one everyone praises. And in American slang from the eighties it meant excellent, which is why old surf films are full of "rad".
1adjectivesweepingReaching the deepest, most basic parts of something; complete and far-reaching.
“The report called for a radical overhaul of the whole system.”
synonyms: sweeping, fundamental, drastic
2adjectiveradicalSupporting extreme or fundamental political change.
“He joined a radical student group in his second year.”
3nounwantsA person who wants deep and rapid political change.
“The radicals in the party refused to sign the compromise.”
4nounchemistry(in chemistry) an atom or group of atoms with an unpaired electron, quick to react.
“The cream claims to fight the free radicals that age skin.”
From Middle English radical, from Latin radicalis, meaning of or belonging to the root. The English word that shows the same picture is grassroots: start at the bottom, at the root, and everything above it changes.
Proto-Indo-European
*wréh₂ds
Latin
rādīcālis — of or pertaining to the root, having roots, radical
Middle English
radical
English, today
radical
Middle English radical, from Latin rādīcālis (“of or pertaining to the root, having roots, radical”). Compare grassroots.
Etymology from Wiktionary, CC BY-SA