niter n (KNO3) used especially as a fertilizer and explosive Usage(s) Yeah, let's pull an all niter to regulate 16th of our economy. Favorite drugs were "mercurials, calomel, opium, niter, Glauber's salts, Dover's powders, jalap, Peruvian barkand by the 1840s, quinine" in heroic doses. Synonym(s) potassium nitrate saltpeter saltpetre nitre