There are multiple origins and meanings for the name:
1. Comes from the Greek words (Ρέα) meaning - "flightless bird", but a tradition embodied in Plato and in Chrysipus connected with the word (ῥέω) [reo] - "flow, stream", or comes from the word (ρόδι) meaning - "pomegranate".
Rhea was the Titaness daughter of Uranus the sky and Gaia the earth, in Greek mythology, mother of the gods. In earlier traditions, she was strongly associated with Gaia and Cybele, the Great Goddess, and was later seen by the classical Greeks as the mother of the Olympian gods and goddesses, though never dwelling permanently among them on Mount Olympus. The Romans identified Rhea with the Goddess Ops.
The name of the bird species rhea is derived from the goddess name Rhea. The second largest moon of the planet Saturn is named after her.
2. Hindi name (रिया) meaning - "singer; river; poppy (flower)"