Skip to Content
Medical Term:


Pronunciation: hā′lō


  1. A reddish yellow ring surrounding the optic disc, due to a widening of the scleral ring making the deeper structures visible.
  2. An anular flare of light surrounding a luminous body or a depigmented ring around a mole.
  3. A circular metal band used in a halo cast or halo brace, attached to the skull with pins.

See: halo nevus

Synonym(s): areola4

[G. halōs, threshing floor on which oxen trod a circle; the halo round the sun or moon]