What is "bardiya"

Bardia or Bardiya ( Bardiya; Smerdis) (possibly died 522 BC) was a son of Cyrus the Great and the younger brother of Cambyses II, both Persian kings. There are sharply divided views on his life. He either ruled the Achaemenid Empire for a few months in 522 BC, or was impersonated by a magus called Gaumāta.