British Dictionary definitions for cyclopentadiene
cyclopentadiene
/ˌsaɪkləʊˌpɛntəˈdaɪiːn/
noun
1.
a colourless liquid unsaturated cyclic hydrocarbon obtained in the cracking of petroleum hydrocarbons and the distillation of coal tar: used in the manufacture of plastics and insecticides. Formula: C5H6