What is the name of the rainbow bridge in Norse mythology?

The rainbow bridge in Norse mythology is called Bifröst.

Bifröst is the shining or burning bridge connecting Midgard, the human world, with Asgard, the home of the gods. It is more than a colorful roadway: the bridge represents a cosmic link between different realms. The Prose Edda describes it as having three colors and great strength, while also warning that it will eventually break.

The bridge is guarded by Heimdallr, who lives at Himinbjörg where Bifröst reaches heaven. The gods use it to travel to their daily assembly near the well of Urðarbrunnr. Thor is the notable exception: he usually crosses the rivers beneath the bridge rather than riding over it.

Older poetic sources call the bridge Bilröst, and it is also called Ásbrú, meaning “the Æsir’s bridge.” These names can cause confusion, as Himinbjörg is the guard’s dwelling and Gjallarbrú is a separate bridge associated with the underworld. During Ragnarök, the forces of Muspell are prophesied to shatter Bifröst.