The outermost region of the sun's atmosphere; visible during a solar eclipse; SYN. corona.
radiant light around head or body of holy personage

ETYM Latin halos, acc. halo, Greek alos a thrashing floor, also (from its round shape) the disk of the sun or moon, and later a halo round it; cf. Greek eilyein to enfold, elyein to roll round, Latin volvere, and Eng. voluble.
A circle of light around the sun or moon.