An Etymological Dictionary of Astronomy and Astrophysics

A silvery-white metallic chemical element; symbol K (from
L. kalium “potash”). Atomic number 19; atomic weight 39.0983; melting point 63.25°C; boiling point 760°C.

Etymology (EN): Coined by the English chemist Sir Humphrey Davy (1778-1829), who first isolated it in 1807 from electrolysis of caustic potash (KOH); from Mod.L. potassa, Latinized form of E. potash + -ium.