Source : Webster's Revised Unabridged Dictionary (1913)

Cacodyl \Cac"o*dyl\, n. [Gr. ??????? ill-smelling (????? bad +
   ????? to smell) + -yl.] (Chem.)
   Alkarsin; a colorless, poisonous, arsenical liquid,
   {As2(CH3)4}, spontaneously inflammable and possessing an
   intensely disagreeable odor. It is the type of a series of
   compounds analogous to the nitrogen compounds called
   hydrazines. [Written also {cacodyle}, and {kakodyl}.]