Ponzu (ポン酢) is a citrus-based sauce commonly used in Japanese cuisine. It is tart, with a thin, watery consistency and a dark brown color. Ponzu shōyu or ponzu jōyu (ポン酢醤油) is ponzu sauce with soy sauce (shōyu) added, and the mixed product is widely referred to as simply ponzu.

The term originally came into the Japanese language as ponsu as a borrowing of the now-obsolete Dutch word pons, meaning punch as in a beverage made from fruit juices. The sour nature of this sauce led to the final su being spelled with the character 酢 (su) meaning vinegar.

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