一 (yī) — one

一 (yī)

The number one, written as a single horizontal stroke; its tone changes depending on what follows: yí before 4th-tone syllables, yì before 1st, 2nd, or 3rd-tone syllables.

Meanings

1. [number] One, the digit 1.
2. [adverb] Once, as soon as (in patterns like 一…就…: as soon as… then…).
3. [determiner] A, an (indefinite article function before measure word + noun).

Example Sentences

我有一个姐姐。 Wǒ yǒu yī gè jiějie. I have one older sister.

他一说话，大家就安静了。 Tā yī shuōhuà, dàjiā jiù ānjìng le. As soon as he spoke, everyone fell quiet.

给我一杯水，好吗？ Gěi wǒ yī bēi shuǐ, hǎo ma? Could you give me a glass of water?

这件事只有一个办法。 Zhè jiàn shì zhǐyǒu yī gè bànfǎ. There is only one solution to this matter.

Collocations

Memory Hook

一 is literally one horizontal stroke — the simplest number in any writing system. One line, one meaning: one.