English edit

 
two fused cyclopropane rings

Etymology edit

bi- +‎ cyclobutane

Noun edit

bicyclobutane (plural bicyclobutanes)

  1. (organic chemistry) A bicyclic hydrocarbon consisting of two separate cyclobutane rings joined by a single bond.
  2. (organic chemistry) A highly strained bicyclic hydrocarbon consisting of two fused cyclopropane rings.