Dānu, a Hindu primordial goddess, is mentioned in the Rigveda, mother of the Danavas. The word Danu described the primeval waters which this deity perhaps embodied. In the Rigveda (I.32.9), she is identified as the mother of Vritra, the demonic serpent slain by Indra. In later Hinduism, she becomes the daughter of Daksha and the consort of Kasyapa.
As a word for "rain" or "liquid", dānu is compared to Avestan dānu "river", and further to river names like Don, Danube, Dneiper, Dniestr, etc. There is also a Danu river in Nepal. The "liquid" word is mostly neutral, but appears as feminine in RV 1.54.