A sulphate in which the sulphate anion occurs in its smallest possible proportion relative to the other element (i.e. one in which the other element occurs in its lowest oxidation state).
Origin
Early 19th century. From proto- + sulphate.
Definition of protosulphate in US English:
protosulphate
(also protosulfate)
nounˌprəʊtə(ʊ)ˈsʌlfeɪt
Chemistry rare
A sulphate in which the sulphate anion occurs in its smallest possible proportion relative to the other element (i.e. one in which the other element occurs in its lowest oxidation state).