Translation guide
The English word "radical" has several distinct meanings. This guide helps learners choose the right Japanese expression depending on whether they mean extreme change, fundamental nature, a political extremist, a kanji component, or something excellent (slang).
Describing a change, reform, or idea that is thorough, drastic, or goes to the root of something.
A common adjective meaning 'drastic' or 'fundamental', often used with reform, review, or improvement.
抜本的な改革が必要だ。
Radical reform is necessary.
Means 'radical' in the sense of advocating rapid, sweeping change, often in politics or ideology.
彼は急進的な政策を提案した。
He proposed radical policies.
Means 'thorough' or 'radical' in the sense of doing something completely, leaving no stone unturned.
徹底的な見直しを行った。
We carried out a radical review.
Means 'extreme' or 'radical', often with a negative connotation of being too extreme or violent.
過激な発言が問題になった。
His radical remarks caused a problem.
Referring to the root, essence, or fundamental nature of something.
Means 'fundamental' or 'radical' in the sense of going to the root of a matter.
根本的な原因を探る必要がある。
We need to find the radical cause.
Similar to 根本的, but more philosophical, meaning 'radical' as in relating to the origin or source.
A person who supports radical political or social change.
Refers to a radical faction or a person belonging to a radical group.
彼は急進派のリーダーだ。
He is a leader of the radicals.
Often used for extremist or militant radicals, sometimes with violent connotations.
The semantic component of a Chinese character used for dictionary lookup.
The standard term for a kanji radical. Use this when talking about kanji classification.
この漢字の部首は何ですか？
What is the radical of this kanji?
Informal way to say something is awesome, excellent, or extreme in a positive sense.
A very common word meaning 'the best' or 'awesome'. Not a direct translation of 'radical' but conveys the same enthusiastic approval.
その映画、最高だった！
That movie was radical!
Slang meaning 'amazing' or 'insane' (in a good way). Very casual, used by younger people.
Older slang (from 80s/90s) meaning 'cool' or 'stylish'. Similar vintage to English 'radical'.
そのジャケット、イカしてるね。
That jacket is radical.
The radical sign (√) or the root of a number.
The mathematical term for the radical symbol (√).
根号の中の数字を計算してください。
Calculate the number under the radical.
Commonly used in school math to mean 'square root' or the radical sign. From English 'root'.
An atom or molecule with an unpaired electron.
The formal chemical term for a free radical.
遊離基は反応性が高い。
Free radicals are highly reactive.
Loanword from English, commonly used in chemistry contexts.
ラジカル重合について研究している。
I'm researching radical polymerization.
When using 'radical' as slang (meaning 'awesome'), do not directly translate it as 急進的 or 過激. Those words have political/extreme connotations. Instead, use 最高 or ヤバい for a natural, positive expression.
抜本的 is used for reforms, changes, or improvements that are drastic and thorough. 根本的 is used for causes, problems, or solutions that are fundamental or go to the root. While they overlap, 抜本的 implies action and change, while 根本的 implies essence and basis.
この問題には抜本的な解決策が必要だ。
We need a radical solution to this problem.
彼は教育に関して急進的な考えを持っている。
He holds radical views on education.
This is a radical problem.
Radicals carried out a terrorist attack.
Isn't this song radical?
The square root of 2 is an irrational number.