di·a·treme 
(dīə-trēm′)
(dīə-trēm′)n.
A volcanic pipe that is filled with breccia, formed by a subterranean gaseous explosion.
[Greek diatrēma, foramen (of a nerve), dugout canoe : dia-, dia- + trēma, perforation; see terə1 in the Appendix of Indo-European roots.]