peroxyacetyl nitrate
noun
per·oxy·ace·tyl nitrate pə-ˌräk-sē-ə-ˈsē-tᵊl- 
-ˈa-sə-tᵊl-,
-ˌtēl-
: a toxic compound C2H3O5N found especially in smog
Word History
First Known Use
1963, in the meaning defined above
Medical Definition
peroxyacetyl nitrate
noun
per·oxy·ace·tyl nitrate pə-ˌräk-sē-ə-ˈsēt-ᵊl-, -ˈas-ət-; -ˈas-ə-ˌtēl-
: a toxic compound C2H3O5N irritating to the eyes and upper respiratory tract that is formed by the action of sunlight on volatile organic compounds and oxides of nitrogen and is found especially in smog —abbreviation PAN