The story
local + hot + bubble. From being a bubble of hot gas in local space.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A supershell surrounding the Solar System in the Milky Way Galaxy. A region of low density hot gas in the zone of space in the Galaxy immediately surrounding the Solar System. Full definition →
local + hot + bubble. From being a bubble of hot gas in local space.
Etymology from Wiktionary, CC BY-SA 4.0.