Nimbus

n. pl. L. Nimbi (#), E. Nimbuses (#).
  1. (Fine Arts) A circle, or disk, or any indication of radiant light around the heads of divinities, saints, and sovereigns, upon medals, pictures, etc.; a halo. See Aureola, and Glory, n., 5.
  2. (Meteor.) A rain cloud; one of the four principal varieties of clouds. See Cloud.

“The nimbus is of pagan origin.” “As an attribute of power, the nimbus is often seen attached to the heads of evil spirits.” Fairholl.