Webster's Revised Unabridged Dictionary · 1913

Butylene

Butylene ({not transcribed}) , noun

[From Butyl.]

1.
(Chemistry) Any one of three metameric hydrocarbons, C4H8, of the ethylene series. They are gaseous or easily liquefiable; -- called also butene.
2.
the hypothetical divalent radical -(CH2)4-; -- used in combining forms; as, butylene diamine.