\Or"pi*ment\, n. [F., fr. L. auripigmentum; aurum gold
+ pigmentum pigment. Cf. {Aureate}, {Pigment}, {Orpin},
{Orpine}.] (Chem.)
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.