noun
a soft, silver-white, waxlike metallic chemical element, one of the alkali metals, that oxidizes rapidly when exposed to air: it occurs abundantly in nature in the form of its salts, which are used in fertilizers, glass, etc.: symbol, K; at. no., 19
Origin:
ModL: so named (1807) < potassa < Du potasch, potash, by Humphrey Sir Humphry Davy, who first isolated it from potash