potash
noun /ˈpɒtæʃ/
/ˈpɑːtæʃ/
[uncountable]- a chemical containing potassium, used to improve soil for farming and in making soapWord Originearly 17th cent.: from pot-ashes, from obsolete Dutch potasschen, originally obtained by leaching vegetable ashes and evaporating the solution in iron pots.