phos·gene 
(fŏsjēn′, fŏz-)
(fŏsjēn′, fŏz-)n.
A colorless gas, COCl2, having an odor similar to mown or moldy hay, used as a poison gas and in making resins, plastics, and dyes.
[French phosgène : Greek phōs, light; see PHOS- + French -gène, -gen.]