paracyanogen
/ˌparəsʌɪˈanədʒ(ə)n/Chemistry
noun
A solid polymer of cyanogen formed in small quantities when cyanogen is prepared, e.g. by heating mercury (ii) cyanide.
Origin
Mid 19th century; earliest use found in George Fownes (1815–1849), chemist. From para- + cyanogen.