Definition
一旦 (yī dàn) means 'once' — it introduces a condition that, as soon as it happens, triggers a result (often with 就 in the main clause). It's more specific than 如果 (if), which is purely hypothetical, and more conditional than 当 (when), which just marks time. 一度 (yī dù) is unrelated: it means 'at one time in the past'.
adverb
once (sth happens, then...)in caseif and when
Easily confused
- 一早yī zǎolook-alikeearly in the morning; at dawn
Examples
- 一旦，。yī dàn nǐ tōngguò le kǎoshì, jiù kěyǐ qù lǚyóu le.Once you pass the exam, you can go traveling.
- 一旦，。yī dàn zhǎo dào gōngzuò, wǒ jiù bānjiā.Once I find a job, I'll move.
- 一旦，。yī dàn tā zhīdào le zhè jiàn shì, tā yídìng huì shēngqì de.Once he finds out about this, he's bound to get angry.
Grammar
Browse more HSK 5 words or search the full 43,000-word dictionary.