一旦 (yī dàn) — once (sth happens, then...); if and when | TongTong Chinese Dictionary

Definition

A conditional adverb meaning 'once / if' — used at the start of a clause to mean the moment something happens. Stronger and more literary than 如果; 倘若 is even more formal.

adverb

once (sth happens, then...)if and when

Examples

一旦，。
yī dàn Nǐ tōng guò le kǎo shì, jiù kě yǐ qù lǚ yóu le.
Once you pass the exam, you can go traveling.
一旦，。
yī dàn Zhǎo dào gōng zuò, wǒ jiù bān jiā.
Once I find a job, I'll move.
一旦，。
yī dàn Tā zhī dào le zhè jiàn shì, tā yí dìng huì shēng qì de.
Once he finds out about this, he's bound to get angry.

Origin

Compound word

构词法gòucífǎ

偏正piānzhèngModifier + head

The first part narrows down the second: it says what kind of thing the head is.

From 一旦, 'one day', it means once or if and when.

Characters in this word

An abstract idea shown by a mark or a diagram rather than by a picture of an object.

一 is drawn as one horizontal stroke, marking the number one.

Most characters — around four in five — are built this way: one part hints at the meaning, the other at the pronunciation.

Meaning part形符xíngfú

Sound part声符shēngfú

丁

丁dīng旦dàn

The sound has drifted apartThe sound part was a clue two thousand years ago — it often still helps, but not always.

旦 combines 日 (sun/day) with 丁 as a sound part; the story about the sun rising over a line is not the original explanation.

Grammar

Full explanation →

Appears in

HSK 3.0 Level 5 HSK 2.0 Level 5 Cause, Effect & Logic 2000 Most Frequent Chinese Words 3000 Most Frequent Chinese Words 5000 Most Frequent Chinese Words

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