an acid phosphate, esp. a mixture mainly of monobasic calcium phosphate and gypsum, made by treating bone, phosphate rock, etc. with sulfuric acid and used as fertilizer
- An acid phosphate.
- A mixture of gypsum and monobasic calcium phosphate resulting from the action of sulfuric acid on phosphate rock, used as a fertilizer.
(countable and uncountable, plural superphosphates)