noun ( pl. haloes or halos )
1. a disk or circle of light shown surrounding or above the head of a saint or holy person to represent their holiness.
• the glory associated with an idealized person or thing: he has long since lost his halo for many ordinary Russians.
2. a circle of white or colored light around the sun, moon, or other luminous body caused by refraction through ice crystals in the atmosphere.
verb ( haloes, haloing, haloed ) [ with obj. ] surround with or as if with a halo.
ORIGIN mid 16th cent. (denoting a circle of light around the sun, etc.): from medieval Latin, from Latin halos, from Greek halōs ‘disk of the sun or moon.’
source | Oxford Dictionaries