一体
ittai
Emphasis; what on earth?
Adds emphatic bewilderment to a question, like saying 'what on earth' or 'who in the world'.
How to form it
Placed directly before the question word (e.g., 誰, 何, どこ, どうして) in a question. No specific verb form is required; it modifies the interrogative.
What it means
一体 is an adverb that injects a sense of puzzlement, frustration, or urgency into a question. It often appears in rhetorical questions where the speaker truly cannot understand or doubts the answer. You'll see it in both casual and formal speech, but it's more common in conversation than in writing.
When you use 一体, the question feels stronger: it implies 'I've been thinking about this, but I really can't figure it out.' For example, '一体何してるの？' sounds more exasperated than just '何してるの？' Be careful not to overuse it in polite requests—it can sound confrontational if not softened with の/んですか.
Example sentences
一体誰がそんなことを言ったんですか。
Ittai dare ga sonna koto o itta n desu ka.
Who on earth said something like that?
一体どうして彼は来なかったんだろう。
Ittai doushite kare wa konakatta n darou.
Why in the world didn't he come?
あの音は一体何だろう。
Ano oto wa ittai nan darou.
What on earth is that noise?
Don’t confuse it with
いったい vs. ぜんたい (全体)
Looks similar to 全体 as a noun meaning 'whole', but as an adverb it's written 一体 and always precedes a question word. 全体 is used in phrases like 全体像 (overall picture) and never adds bewilderment to a question.
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Used in both spoken and written Japanese, but it's more at home in casual or semi-formal conversation; in very formal writing you might avoid it for a neutral tone.
Next in the N3 path
45Questions
What does 一体 mean?
Emphasis; what on earth?. Adds emphatic bewilderment to a question, like saying 'what on earth' or 'who in the world'.
How do you form 一体?
Placed directly before the question word (e.g., 誰, 何, どこ, どうして) in a question. No specific verb form is required; it modifies the interrogative.
Example of 一体 in a sentence
一体誰がそんなことを言ったんですか。 — Who on earth said something like that?
いったい vs. ぜんたい (全体) — what is the difference?
Looks similar to 全体 as a noun meaning 'whole', but as an adverb it's written 一体 and always precedes a question word. 全体 is used in phrases like 全体像 (overall picture) and never adds bewilderment to a question.
What JLPT level is 一体?
JLPT N3 (intermediate), number 44 of 182 in Nihoner's learning order for N3.
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