phosgene

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.

Producing, or produced by, the action of light; — used specifically to designate a gas also called carbonyl chloride. See carbonyl.

A reactive chemical substance (COCl2), also called carbonyl choride, used in synthesis of numerous substances. In the First Worlds War it was also used as a poisonous gas in combat.

Alternative form of carbonyl chloride.

a colorless poisonous gas that smells like new-mown hay; used in chemical warfare