盐水 (yán shuǐ) literally means 'salt water' — a simple compound noun formed by combining 盐 (yán, 'salt') and 水 (shuǐ, 'water'). It refers to water with dissolved salt, commonly used in everyday contexts such as cooking, cleaning, medical care, and food preservation. Unlike the more technical term 生理盐水 (shēnglǐ yánshuǐ, 'physiological saline'), 盐水 is neutral and widely understood across all age groups and regions.

This word appears frequently in health-related situations — for example, gargling with warm salt water to soothe a sore throat, rinsing contact lenses, or cleaning minor wounds. It may also describe naturally occurring salt water, like seawater, though 海水 (hǎishuǐ) is more precise for that meaning. In informal speech, 盐水 is often used without specifying concentration, implying a mild, household-strength solution — typically one teaspoon of salt per cup of warm water.