科隆香水（也译为古龙水；法语：Eau de Cologne，德语：Kölnisch Wasser，意思为“科隆之水”）是一种含有2-3%精油含量的清淡香水。此香水最先在1709年由意大利人，吉欧凡尼·马利亚·法利纳（Giovanni Maria Farina），在德国的科隆推出。因为广受欢迎，其他品牌的古龙水也相续被推出。其中包括以其店铺门牌为名的4711科隆香水。

由于科隆香水在推出时受到男性族群的爱用，使得其另一译名「古龙水」在中文环境中，经常成为男用香水的代名词。

Eau de Cologne (French: [o d(ə) kɔlɔɲ]; German: Kölnisch Wasser [ˈkœlnɪʃ ˈvasɐ]; lit. “Water of Cologne”), or simply cologne, is a perfume originating from Cologne, Germany. Originally mixed by Italian-born Johann Maria Farina in 1709, it has since come to be a generic term for scented formulations in typical concentration of 2%–5% and also more depending upon its type essential oils or a blend of extracts, alcohol, and water. In a base of dilute ethanol (70%–90%), eau de cologne contains a mixture of citrus oils including oils of lemon, orange, tangerine, clementine, ****, lime, grapefruit, blood orange, and bitter orange. It can also contain oils of lavender, rosemary, thyme, oregano, petitgrain (orange leaf), jasmine, olive, oleaster, and tobacco.