means A soft, silvery metallic element (symbol K, atomic number 19) essential to life, especially for nerve and muscle function, and found abundantly in foods like bananas.

from Named in the early 19th century from 'potash' — literally the 'pot ash' left when you soaked wood ashes in a pot and boiled the water away, an old way of extracting the stuff. Humphry Davy isolated the metal and called it 'potassium' after that potash. The symbol K comes from the Latin 'kalium,' which traces back to Arabic 'al-qali,' 'the ashes of plants' — the same root that gives us 'alkali.'