E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The demon that causes eclipses. One day Rahu stole into Valhalla to quaff some of the nectar of immortality. He was discovered by the Sun and Moon, who informed against him, and Vishnu cut off his head. As he had already taken some of the nectar into his mouth, the head was immortal, and he ever afterwards hunted the Sun and Moon, which he caught occasionally, causing eclipses. (Hindu mythology.)