o-chlorobenzylidene malononitrile

o-chlor·o·ben·zyl·i·dene mal·o·no·ni·trile

(ōr'thō-klōr-ō-bĕn-zili-dēn măl-ō'nō-nī'trīl') A compound (NATO code CS) widely used as a lacrimator and riot-control agent.