what is superphosphate
Definition of SUPERPHOSPHATE. 1. : an acid phosphate. 2. : a soluble mixture of phosphates used as fertilizer and made from insoluble mineral phosphates by treatment with sulfuric acid. See superphosphate defined for kids.ADVERTISEMENT.. : an acid phosphate. 2. : a soluble mixture of phosphates used as fertilizer and made from insoluble mineral phosphates by treatment with sulfuric acid.