ˈ ̷ ̷ ̷ ̷ˌprēn noun
( -s )
Etymology: probably from is- + pr- (from propyl ) + -ene
: a flammable liquid diolefin hydrocarbon CH 2 = C(CH 3 )CH = CH 2 obtained usually by heating rubber or turpentine (sense 2) or in cracking petroleum and used chiefly in making synthetic rubber; 2-methyl-1,3-butadiene — see polyisoprene , terpene