The story
Blend of ultrahot + hot jupiter. From being a type of gas giant planet much hotter than most jupiter-class planets.
Etymology from Wiktionary, CC BY-SA 4.0.
ultra-hot jupiter
Today it means: A giant planet, of similar mass to that of Jupiter, which orbits close enough to its sun to become tidally locked, and whose day-side atmosphere has therefore heated up so much, as to break apart most molecules, leaving atomic gas. The day-side atmosphere has the temperature and spectral characteristics of a star's surface. Full definition →