raw water; untreated water
Refers to water in its natural state before any purification or treatment process, often used in contexts like water treatment plants or environmental discussions.
At the water purification plant, raw water is filtered and turned into drinking water.
atomic and hydrogen bombs; nuclear and thermonuclear bombs
Compound of 原 (gen, 'original, raw') and 水 (sui, 'water'). The exact historical derivation is uncertain, but the term is a straightforward technical compound.