Home›Browse›P›potassium alumpotassium alumOur editors are putting together more complete content — check back in about 20 minutespotassium alumpotassium alum — nounnoun1. a double sulfate used as a mordant in dyeing and as a styptic1.nounDefinitiona double sulfate used as a mordant in dyeing and as a stypticExamplePotassium alum is commonly used in water purification.