Source : Webster's Revised Unabridged Dictionary (1913)

Crotonylene \Cro*ton"y*lene\ (kr?-t?n"?-l?n), n. [Crotonic +
   acet-ylene.] (Chem.)
   A colorless, volatile, pungent liquid, {C4H6}, produced
   artificially, and regarded as an unsaturated hydrocarbon of
   the acetylene series, and analogous to crotonic acid.