Orpiment (?), n. [F., fr. L. auripigmentum; aurum gold + pigmentum pigment. Cf. Aureate, Pigment, Orpin, Orpine.] (Chem.) Arsenic sesquisulphide, produced artificially as an amorphous lemon-yellow 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.
[1913 Webster]

Our orpiment and sublimed mercurie. Chaucer.
[1913 Webster]

Red orpiment, realgar; the red sulphide of arsenic. -- Yellow orpiment, king's yellow.
[1913 Webster]