vinegar diluted with water; vinegar-water mixture
Refers to a mixture of vinegar and water, often used in cooking or cleaning. The term is straightforward and has no special register or rarity.
When washing vegetables, it's good to use vinegar diluted with water.
In this recipe, you soak it in vinegar-water before cooking.
Compound of 酢 (す, 'vinegar') and 水 (みず, 'water'), with sequential voicing (連濁) changing みず to みず. The term literally means 'vinegar water'.