D defs.my
Entry 1 sense Webster, 1913

Congo red

· IPA
01 An artificial red dye from which the Congo group received its name. It is also widely used either in aqueous solution or as test paper (Con…
  1. 1.
    An artificial red dye from which the Congo group received its name. It is also widely used either in aqueous solution or as test paper (Congo paper) for the detection of free acid, which turns it blue.(Chem.)