\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}).