(Science: chemistry) arsenic sesquisulphide, produced artificially as an amorphous lemonyellow powder, and occurring naturally as a yellow crystalline mineral; formerly called auripigment. It is used in king's yellow, in white indian fire, and in certain technical processes, as indigo printing. Our orpiment and sublimed mercurie. (Chaucer) red orpiment, realgar; the red sulphide of arsenic. Yellow orpiment, king's yellow.
Origin: F, fr. L. Auripigmentum; aurum gold _ pigmentum pigment. Cf. Aureate, Pigment, Orpin, Orpine.