一体なんだ？
ittai nan da?
In Japanese, "what the hell" can be expressed as 一体なんだ？ (ittai nan da?) If unsure, use 一体なんだ？ Wiktionary also lists 一体全体なんだ？ (ittai-zentai nan da?) and なんだよ、これ？ (nan da yo, kore?).
Meaning: an intensive form of what (phrase)
Ways to say it
| Japanese | Romanization (Wiktionary) |
|---|---|
| 一体なんだ？ | ittai nan da? |
| 一体全体なんだ？ | ittai-zentai nan da? |
| なんだよ、これ？ | nan da yo, kore? |
These expressions are used as an intensive form of "what" to express disbelief, confusion or intense curiosity. The term 一体 is almost exclusively used in interrogative sentences (questions).
What does it mean word for word?
The word 一体 literally means "one body" or "one unit", but it functions as an intensive particle meaning "on earth" or "the hell" when used in questions.
Which one should you use?
While 一体なんだ？ focuses on the confusion of the situation, なんだよ、これ？ focuses more on frustration or annoyance with the object itself.
Is there a formal and an informal way to say it?
The form 一体なんだ？ is informal and should not be used in polite or professional settings. The expressions なんだよ and なんだこれ are also casual and informal.
How do you pronounce it?
ittai nan da?
Did you know?
- The word 一体 is also used in a completely different context to mean 'unification' or 'becoming one'. In this sense, it describes things merging into a single entity rather than expressing confusion.
- The length of the phrase matters. Adding '全体' to create 一体全体 makes the expression even more dramatic and heavy, almost like saying 'what in the entire wide world' in English.
- While 一体なんだ？ expresses a strong 'what the hell', Japanese speakers rarely use literal swear words in these phrases. Instead, they rely on ending particles and a sharp tone of voice to convey anger.
Examples in context
- くそ、また電車が遅れているWhat the hell, the train is delayed again.
- 一体なんだ？ この音は。ittai nanda? kono oto wa.What the hell is this sound?
- 一体なんだ？ あの計画は。ittai nanda? ano keikaku wa.What the hell is that plan?
- 一体なんだ？ この状況は。ittai nanda? kono joukyou wa.What the hell is this situation?
Example conversation
The two siblings find a strange object in the living room.
- 陽葵 Himari陽太、見て。一体なんだ？Youta, mite. Ittai nanda?Youta, look. What the hell is this?
- 陽太 Yota分からないけど、変な形だね。Wakaranai kedo, hen na katachi dane.I don't know, but it's a strange shape.
- 陽葵 Himari誰がここに置いたんだろう？Dare ga koko ni oita ndarou?I wonder who put it here?
- 陽太 Yotaお父さんじゃないかな。Otousan janai kana.Maybe it was Dad.
Sources
- Wiktionary, “what the hell” translations, CC BY-SA 4.0, dump of 2026-09-26.
