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Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A white amorphous or granular substance which consists principally of potassium carbonate and has a strong alkaline reaction. It is obtained by lixiviating wood ashes and evaporating the lye, and has been an important source of potassium compounds. It is used in making soap, glass, etc. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.