from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. General name of a number of orange dyes of very complex composition. They are sulphonic acids.
from the GNU version of the Collaborative International Dictionary of English
- n. 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 (Tropæolum).
from The Century Dictionary and Cyclopedia
- n. The general name of a number of orange dyes of very complex composition. They are sulphonic acids.
Tropæolum + -in (Wiktionary)