Definition - What does Indra mean?
Indra is the king of the Hindu gods. According to Hinduism, Indra is the god of heaven, war and thunder and storm. In Sanskrit, indu means "a drop" and ra means "possessing"; hence, Indra means "possessing drops of rain."
Indra is also worshiped by followers of Buddhism and Jainism.
Yogapedia explains Indra
Indra was the most worshiped god during Vedic times. The "Rig Veda" dedicated many hymns in praise of Indra; however, his popularity now pales in comparison with other famous Hindu gods like Shiva and Vishnu.
In the Yoga Sutras, Patanjali wrote a story about Indra in which the mighty god took the form of a pig and lead a happy life on Earth. Patanjali further stated that Indra refused to go with the gods who came down to Earth and requested he come back to heaven. It was only after the pig form was killed that Indra realized what he was doing and returned to his rightful place with the gods.
A great warrior, Indra's weapon is the vajra, meaning "thunderbolt." The white elephant he rides on is named Airavata. The battle against Vritra, the asura who was the leader of dasas, is considered the most important battle waged by Indra among his innumerable wars against various enemies. Also the lord of devas, his role is to protect the gods from evil forces.