(1):

(n.) A celestial crown or accidental glory added to the bliss of heaven, as a reward to those (as virgins, martyrs, preachers, etc.) who have overcome the world, the flesh, and the devil.

(2):

(n.) The circle of rays, or halo of light, with which painters surround the figure and represent the glory of Christ, saints, and others held in special reverence.

(3):

(n.) A halo, actual or figurative.

(4):

(n.) See Areola, 2.