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Webster 1913 Edition
Sulphacid
Sulph-ac′id
,Noun.
 [
Sulpho- 
+ acid
.] (Chem.) 
An acid in which, to a greater or less extent, sulphur plays a part analogous to that of oxygen in an oxyacid; thus, thiosulphuric and sulpharsenic acids are sulphacids; – called also , 2. 
sulphoacid
. See the Note under Acid
, Noun.