Dictionary › 一旦

一旦

yī dàn

Old HSK 5 HSK 3.0 level 5 2-character word

一旦 (yī dàn) means "once (sth happens), in case". It is an HSK 3.0 level 5 word, and was HSK 5 in the old six-level list.

What 一旦 means

1. in case (sth happens)
2. if
3. once (sth happens, then...)
4. when
5. in a short time
6. in one day

The characters in 一旦

• 一yīone; single; a (article)
• 旦dàn(literary) dawn; daybreak; dan, female role in Chinese opera…

Example sentences

• 一旦过了河, 你就安全了。
  Once across the river, you are safe.
• 她一旦开始说话，就很难让她停下来。
  Tā yīdàn kāishǐ shuōhuà, jiù hěn nán ràng tā tíngxiàlái.
  Once she starts talking, she is hard to stop.
• 一旦养成了坏习惯，就很难改回来了。
  A bad habit, once formed, is difficult to get rid of.
• 一旦爆发核战争，受苦的将会是全人类。
  Yīdàn bàofā hézhàn zhēng, shòukǔ de jiānghuì shì quán rénlèi.
  All humanity will suffer if a nuclear war breaks out.
• 坏习惯一旦被养成，便不能简单地改正。
  Once you have formed a bad habit, you can't get rid of it easily.
• 你一旦不做个乖孩子，圣诞老人就不会来噢。
  Nǐ yīdàn bù zuò ge guāi háizi, Shèngdàn Lǎorén jiù bù huì lái o.
  If you don't behave, Santa won't come.

Words containing 一旦

• 毁于一旦huǐ yú yī dàn(idiom) ruined in a short time…

Where 一旦 is taught

In the GraphChinese course it is part of Conditional & Hedging Words (HSK 5), each one a topic in the dependency graph of HSK 1–6 that opens only once its prerequisites are solid.

Go deeper

• Every HSK 5 word, with the rest of its level.
• The four tones and the neutral tone, to read yī dàn correctly.
• Look up another word in the free dictionary.