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. [ 1913 Webster ]
n. any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays. Syn. -- sunflower. [ WordNet 1.5 ]