Tropaeolin \Tro*p[ae]"o*lin\, n. (Chem.) A name given to any one of a series of orange-red dyestuffs produced artificially from certain complex sulphonic acid derivatives of azo and diazo hydrocarbons of the aromatic series; -- so called because of the general resemblance to the shades of nasturtium ({Trop[ae]olum}).