Webster’s Revised Unabridged Dictionary · 1913
Helianthin
He′li·an′thin (hē′lĭ·ăn′thĭn), n. [Prob. fr. L. helianthes, or NL. helianthus, sunflower, in allusion to its color.] (Chem.) An artificial, orange dyestuff, analogous to tropaolin, and like it used as an indicator in alkalimetry; — called also methyl orange.