D defs.my
Entry 1 sense Webster, 1913

Helianthin

· He·li·an·thin · IPA
01 n. An artificial, orange dyestuff, analogous to tropaolin, and like it used as an indicator in alkalimetry; -- called also methyl orange.
  1. 1.
    An artificial, orange dyestuff, analogous to tropaolin, and like it used as an indicator in alkalimetry; -- called also methyl orange.(Chem.) Also: methyl orange