- an orange-yellow, slightly water-soluble powder, C14H14N3NaO3S, used chiefly as an acid-base indicator.
Compare methyl red.
Origin of methyl orange
First recorded in 1880–85
Also called gold orange, helianthine B, orange III, tropaeolin D, tropeolin D.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018