一旦・いったん (ittan)
once (something happens); for a moment; on a temporary basis; for now
Meaning & usage
いったん means once something has happened, the situation changes decisively and the result continues. It is an adverb placed before a clause, commonly in patterns like いったん始めたら, いったん決めれば or いったんすると, followed by a main clause expressing determination, obligation, or an unavoidable outcome. It is not used for a neutral sequence of actions or a static description, so the main clause should show a lasting consequence.
Example sentences 4
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何でもいったんやり始めたら、絶対にあきらめるな。
Once you have begun to do something, never give up.
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いったん約束をしたら、守らなくてはいけない。
Once you have made a promise, you should keep it.
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いったん職業を決めたらむやみに変えてはいけない。
Once you decide to enter a profession, you can't change your mind on a whim.
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いったん結婚したらおしまいだよ。
Once you are married, you are done for.
In past JLPT papers
This came up in 2 past exam questions.
