butylene

n. [ From Butyl. ] 1. (Chem.) Any one of three metameric hydrocarbons, C4H8, of the ethylene series. They are gaseous or easily liquefiable; -- called also butene. [ 1913 Webster ]

2. the hypothetical divalent radical -(CH2)4-; -- used in combining forms; as, butylene diamine. [ PJC ]