ˈzīləˌlēn noun
( -s )
Etymology: International Scientific Vocabulary xylyl + -ene
1. : any of several isomeric bivalent radicals C 8 H 8 derived from the three xylenes by removal of one hydrogen atom from each of two carbon atoms ; especially : any of the three radicals having the formula −CH 2 C 6 H 4 CH 2 −; phenylene-di-methylene
2. : a reactive hydrocarbon CH 2 = C 6 H 4 = CH 2 that is formed by pyrolysis of para -xylene under low pressure followed by quick chilling in a solvent at -80° C and that polymerizes to an insoluble white mass at room temperature — called also para-xylylene, p-xylylene