PIE base ‘to shine, glisten’. See also *dyeu- ‘to shine’, root of Divinity, and *leuk- ‘light’.
Other derivatives include beacon, berry, banner, fantasy, phase, and photo and phosphorous, from Greek phōtos, phōs, phaos ‘light’, used in the New Testament in the Bible.
[Pokorny *bhā-1, bhō-, bhə-, p. 104–105.]