How to say "Watch out!" in Chinese

小心 is a compound word: 小 (small) + 心 (heart), together meaning "be careful" or "take care." It's a fixed expression used as a warning or caution.

Use this to alert someone to immediate danger, like a car coming or a slippery floor. It's direct and urgent, so it's fine to shout it. A common mistake is using it too casually; for a general "be careful" as advice, you'd say 小心一点 (xiǎoxīn yìdiǎn) or 请小心 (qǐng xiǎoxīn).