softener

a substance used in washing (clothing or hair) to make things softer

a substance added to plastics or other materials to make them more pliable

a substance (such as sodium chloride) that lessens the hardness of water by replacing calcium and magnesium ions with sodium ions and so gives the water more efficient sudsing power

any of a family of glassy minerals analogous to feldspar containing hydrated aluminum silicates of calcium or sodium or potassium; formed in cavities in lava flows and in plutonic rocks