とんでもない

Taken apart

No breakdown is shown for this word: Wiktionary's text for it doesn't give a split that spells the word and joins to its reading, and any other split would be a guess.

In a sentence

We don't have the data for this section. The pinned Tatoeba export has no sentence with a translation that uses this word and passes our filter.

What Wiktionary says

Quoted line by line from Wiktionary's Etymology section for this reading, taken from one dated dump so it can't change underneath us. Nothing below is paraphrased.

• “Many sources consider this to be a shift from 途でもない (to de mo nai, literally “that is not even the way”, idiomatically “extraordinary, unexpected, unreasonable”) or とでもない (to de mo nai, literally “that's not even [whatever came before]”, where the to here is the quotative particle to in reference to whatever was just said previously).”
• “However, citations for tondemonai precede those for todemonai by several decades (tondemonai cited to 1586–99, todemonai to 1638), pointing instead to tondemonai as the original form, and to de mo nai as a later development.”
• “An analysis of the earliest texts indicates that this expression arose first in eastern Japanese dialects. Eastern dialects have a tendency to pre-nasalize voiced consonants, which would suggest that the initial tonde may indeed be to de (from either noun 途 (to, “way”) or particle と (to, quotative)).”
• Hedged“While the ない (-nai) ending does appear to be 無い (nai, “not; is not”), there are no historical attestations of とんでも (tondemo) used separately. The term トンデモ (tondemo, “outrageous, unexpected”) is derived from とんでもない (tondemonai) only in relatively modern usage, such as in the now-dated expression とんでもハップン (tondemo happun) cited to 1950.”
• “Despite surface similarities, the tonde here is almost certainly not derived from とんだ (tonda, “extraordinary, unexpected”).”

Source: Wiktionary: とんでもない (dump of 2026-09-02), available under CC BY-SA 4.0. Reading, meaning and part of speech from JMdict, and kanji readings from KANJIDIC2 (EDRDG).

What the labels mean

和語 Native Japanese

Words that were already Japanese before Chinese vocabulary arrived — usually written with kun'yomi and often short.

Sound change

The pronunciation shifted over the centuries.