The ultraviolet catastrophe, also called the Rayleigh–Jeans catastrophe, was the prediction of late 19th century to early 20th century classical physics that an ideal black body at thermal equilibrium would emit an unbounded quantity of energy as wavelength decreased into the ultraviolet range. Wikipedia

The prediction by classical physics that a black body will emit radiation at infinite power Wikipedia Disambiguation

Classical physics prediction that black body radiation grows unbounded with frequency Wikidata

A fault in classical physics, from the Rayleigh's Law/Rayleigh-Jeans Law outcomes at short wavelengths/high frequencies, that causes infinite amplification of shorter wavelength/higher frequency radiation inside a cavity, due to the application of equipartition theorem on black body radiation within a cavity. Wiktionary