Meaning & Usage
✨ Basic Meaning
What on earth; how in the world; really; generally (as an intensifier).
🎯 Primary Function
An adverb used to intensify an interrogative sentence, adding a tone of strong doubt, confusion, surprise, or exasperation, equivalent to “what in the world,” “who on earth,” etc.
📋 Grammar Structure
Question Word + は/が + 一体 + [Sentence] + か/だろう/のですか
N/A (Used as an intensifier/adverb)
N/A (Used as an intensifier/adverb)
N/A (Used as an intensifier/adverb)
🎭 Usage Contexts
Formal Situations
Used sparingly in formal situations, as its strong emotional tone can be inappropriate. If used, it should be in polite form (e.g., 〜のですか?).
Informal Situations
Very common in casual conversation among friends or family when expressing strong feelings.
Written Language
Appears in dialogue in novels, manga, and sometimes in persuasive essays to convey a rhetorically intense question. Less common in objective reports.
Spoken Language
Its primary domain; adds crucial emotional nuance to questions.
💡 Common Applications
Expressing Strong Confusion or Doubt
Used to intensify a question about location or existence, indicating the speaker is very confused or frustrated.
Example: この部屋の鍵は一体どこにあるんだ？
Expressing Surprise or Disbelief in an Action
Used when something unexpected happens, questioning the underlying reason with strong emotion.
Example: 彼女は一体何があったんだろう？急に泣き出した。
Demanding an Explanation with Frustration
Used when questioning someone’s motives or thoughts in an exasperated manner. This application can sound confrontational.
Example: あなたは一体何を考えているんですか！
Frequency
High in conversational Japanese, especially when expressing strong emotion.
Difficulty
JLPT N3 / N2
Tag:
Example Sentences
Example #1
君、一体そんな変な道具で何をしようとしているの？
Furigana: きみ、いったいそんなへんなどうぐでなにをしようとしているの？
Romaji: Kimi, ittai sonna hen na dōgu de nani o shiyō to shite iru no?
English: What on earth are you trying to do with that strange tool?
Example #2
一体どこからそんな面白いアイデアを得たんですか？
Furigana: いったいどこからそんなおもしろいアイデアをえたんですか？
Romaji: Ittai doko kara sonna omoshiroi idea o etan desu ka?
English: Where in the world did you get such an interesting idea?
Example #3
誰が人に気づかれずに一体こんなことをできたのだろう？
Furigana: だれがひとにきづかれずにいったいこんなことをできたのだろう？
Romaji: Dare ga hito ni kizukarezu ni ittai konna koto o dekita no darō?
English: Who on earth could have done such a thing without anyone noticing?
Example #4
一体どうやってこの製品をそんなに安い値段で売れるのだろうか？
Furigana: いったいどうやってこのせいひんをそんなにやすいねだんでうれるのだろうか？
Romaji: Ittai dō yatte kono seihin o sonnani yasui nedan de ureru no darō ka?
English: How in the world can they sell this product at such a low price?
Example #5
彼は何も言わずにいってしまった。一体なぜ怒ったのだろう？
Furigana: かれはなにもいわずにいってしまった。いったいなぜおこったのだろう？
Romaji: Kare wa nani mo iwazu ni itte shimatta. Ittai naze okotta no darō?
English: He left without a word. Why on earth did he get angry?
Example #6
この不思議な文書には一体どんな秘密が隠されているのだろうか？
Furigana: このふしぎなぶんしょにはいったいどんなひみつがかくされているのだろうか？
Romaji: Kono fushigi na bunsho ni wa ittai donna himitsu ga kakusarete iru no darō ka?
English: What kind of secret is hidden in this mysterious document, I wonder?
Example #7
駅前の工事は、一体いつ終わるんですか？
Furigana: えきまえのこうじは、いったいいつおわるんですか？
Romaji: Ekimae no kōji wa, ittai itsu owarun desu ka?
English: When on earth will the construction work in front of the station be finished? (Expressing impatience)
Example #8
あなたが一体何を言いたいのか分からないので、もう一度説明してください！
Furigana: あなたがいったいなにをいいたいのかわからないので、もういちどせつめいしてください！
Romaji: Anata ga ittai nani o iitai no ka wakaranai node, mō ichido setsumei shite kudasai!
English: I can’t understand what you’re trying to say, so please explain it again!
Example #9
ちょっと、一体最後になって契約をキャンセルするつもりですか？
Furigana: ちょっと、いったいさいごになってけいやくをキャンセルするつもりですか？
Romaji: Chotto, ittai saigo ni natte keiyaku o kyanseru suru tsumori desu ka?
English: Wait, are you seriously going to cancel the contract at the last minute?
Example #10
探していたのに、一体どこへ行ってしまったんだろう。
Furigana: さがしていたのに、いったいどこへいってしまったんだろう。
Romaji: Sagashiteita noni, ittai doko e itte shimattan darō.
English: I was looking for it everywhere, but where did it go?
Notes & Nuances
📌 Important Points
Requires an Interrogative Word
It must always be used in a question that contains a question word (who, what, when, where, why, how). It adds emotional weight to that question word.
Example: 一体何があったの？
Adds Strong Emotional Intensity
The strong emotion (frustration, disbelief) it conveys makes the question urgent and demanding. It is not used for neutral or factual inquiries.
Example: あなたは一体誰なんですか？
Can Sound Rude or Confrontational
If used without the polite “ですか” or “でしょう,” it can sound confrontational, especially when expressing frustration. Context is key.
Example: 一体何を言いたいんだ。
⚠️ Common Mistakes
❌ 一体、電車が来ますか？
✅ 一体、いつ電車が来るんですか？
‘Ittai’ must be used with a question word (何, 誰, いつ, etc.) to function as an intensifier. Using it with a simple Yes/No question is usually unnatural.
❌ 私は一体誰なのでしょうか。 (Too dramatic/unnatural in objective context)
✅ 私は一体どうすればいいですか。
Avoid using ‘ittai’ with questions about self-identity or rhetorical musings in very formal contexts where a neutral tone is required. It always injects emotion.
❌ 一体、彼は何をしたの？
✅ 彼は一体何をしたの？ (Kare wa ittai nani o shita no?)
While it can be used at the beginning, its most natural position is immediately before the verb/predicate or right after the topic/subject.
🏛️ Cultural Context
Politeness Level: Low to Medium. It conveys impatience or doubt, which can sound impolite if directed at a superior or stranger. Use carefully in polite settings.
Social Situations: Most appropriate when speaking with equals, friends, or subordinates, or when expressing genuine shock or strong curiosity that transcends social hierarchy.
Regional Variations: Standard Japanese. No significant regional variations in its use as an adverbial intensifier.
🔍 Subtle Differences
一体 (ittai) vs. 本当に (hontō ni)
Ittai demands an answer with intense confusion or frustration. Hontō ni is a neutral confirmation or general surprise.
When to use: Use 一体 when you are genuinely exasperated or completely bewildered and need an explanation. Use 本当に when expressing general surprise or seeking simple confirmation.
一体 (ittai) vs. まさか (masaka)
Ittai emphasizes the unknown (What on earth?). Masaka emphasizes impossibility or strong denial (No way!).
When to use: Use 一体 when you are asking “why” or “how” something happened. Use まさか when you are saying “I never thought that would happen.”
一体 (ittai) vs. いったいぜんたい (ittai zentai)
いったいぜんたい is an even stronger, more intense, and sometimes slightly older-sounding version of 一体.
When to use: Use 一体 for standard emotional questions. Use いったいぜんたい for maximum dramatic effect or extreme exasperation.
📝 Conjugation Notes
一体 (ittai) is primarily an adverb and does not conjugate. When used as a noun meaning “one body” or “unity,” it can take particles like と (to) or に (ni). (e.g., 二つを一体にする – to make the two into one).
🔊 Pronunciation Tips
The “i” in “ittai” is slightly held (double ‘t’ sound). It is often pronounced with a heightened tone or emphasis to reflect the strong emotion it conveys.
🧠 Memory Tips
Think of the kanji: 一 (one) + 体 (body/form). “What is the *one true form* or *essence* of this situation?” -> “What on earth is going on?” (Focusing on the underlying truth).
Other Grammar
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