supershell

== English == === Etymology === From super- +‎ shell. === Pronunciation === === Noun === supershell (plural supershells) (astronomy) A large region carved out of the interstellar medium by the combination of several supernova shells, leading to a lower density of gas and plasma within than without, larger than any single supernova could create. ==== Synonyms ==== (astronomy): superbubble ==== Coordinate terms ==== (space plasmas):