Which one should you use?
While とんでもない is a versatile way to express that something is unthinkable or absurd, other forms focus on different nuances of a refusal. 絶対にダメです or 絶対にいけません focus on the idea that something is "not allowed", whereas 絶対に無理だよ or 絶対ムリ emphasize that a request is "impossible". Finally, 絶対にありえない is used when something is "unthinkable" or "out of the question".
Is there a formal and an informal way to say it?
とんでもない can be made more polite and suitable for use with superiors or in formal settings by adding です to the end, forming とんでもないです. For formal denials, you can also use 絶対にダメです or 絶対にいけません. In informal situations, you might use 絶対に無理だよ, 絶対ムリ or 絶対にありえない.
How does it change in a sentence?
In its dictionary form, とんでもない functions as an adjective meaning "absurd" or "unthinkable".
How do you pronounce it?
tondemonai
Did you know?
- In the mid-20th century, the expression とんでもハップン combined とんでもない with the English word 'happening' to describe an extraordinary or absurd event.
Examples in context
- とんでもない！Absolutely not!This example shows the use of とんでもない.Tatoeba #5955968 by tatoebane, translation #9008143 by shekitten
- そんなことは、とんでもないです。Sonna koto wa, tondemonai desu.That is absolutely not the case.
- とんでもない！そんなの無理だよ。Tondemonai! Sonna no muri da yo.Absolutely not! That's impossible.
Example conversation
Misaki asks Kenta if he thinks she is a bad person.
- 美咲 Misaki私が悪い人だと思ってる？Watashi ga warui hito da to omotteru?Do you think I am a bad person?
- 健太 Kentaとんでもない！美咲さんは優しいよ。Tondemonai! Misaki-san wa yasashii yo.Absolutely not! You are kind, Misaki.
- 美咲 Misaki本当？よかった。Hontou? Yokatta.Really? I'm glad.
- 健太 Kenta本当だよ、信じて。Hontou da yo, shinjite.It's true, believe me.
Sources
- Pronunciation: Wiktionary entry とんでもない, CC BY-SA 4.0, dump of 2026-09-26.
- Word origins: Wiktionary entries とんでもない, CC BY-SA 4.0.
- Example sentences: Tatoeba CC BY 2.0 FR.
