means A painting technique using pigments suspended in water, applied in translucent washes — and the artwork made by it.

from A plain compound of "water" and "color," assembled in English to name exactly what it is: color thinned with water. "Water" traces back through Old English wæter to a deep Proto-Indo-European root for water (a cousin of Latin unda, "wave," and the Greek hydor behind "hydrant"). "Color" arrived via Old French from Latin color, related to celare, "to conceal" — the idea being a covering or surface hue. The honest English label has been around for the medium since at least the 17th century.