Everyone’s familiar with the word halo in the sense of a circle of light behind or above the head of a saintly person in a painting.
The word halo comes from a Greek word meaning “disk of the sun or moon.” The first recorded use in English of halo with the sense of “light around the head of a holy person or deity” is 1646. However, Egyptians, Greeks, Romans and other non-Christian cultures used the symbol in art to denote divinity or prestige. Gods and rulers were often depicted with halos.
In addition to the halo, artists have used other symbols to denote saintliness or divinity. Writers may find some of the terms for these symbols useful in describing not just supernatural characters, but to convey certain effects of light.
The word nimbus is sometimes used as a synonym for halo, but it has the primary meaning of
a bright or luminous cloud or cloud-like formation supposedly enveloping or surrounding a deity or supernatural being” –OED
The aureole is another word sometimes used as a synonym for halo, but is frequently used to denote a light emanating from the entire body of the holy figure.
The OED offers this note on the definition of aureole:
Didron (Iconographie Chrétienne p. 109) by a strange blunder takes aureola for a diminutive of aura ‘emanation, exhalation,’ and defines it as a mantle of light emanating from and enveloping the body, as distinct from the nimbus, which he confines to the head. This definition, which reverses the historical use both of aureola and nimbus, is not accepted in France (see Littré), but has been copied by Fairholt, and various English Dictionaries.
A diminutive of Latin aureus “golden,” the aureole was used in medieval Christian art to indicate the heavenly crown earned by martyrs and virgins.
The mandorla is “an almond-shaped panel or decorative space, usually framing an image of Christ.” The name comes from the Italian word for “almond.”
One of the many definitions of glory is “the circle of light represented as surrounding the head, or the whole figure, of the Saviour, the Virgin, or one of the Saints.”
The OED gives the word gloriole as a synonym for both aureole and halo.
All of these terms have other uses. For example, nimbus comes from a word for cloud and, like halo, has weather applications as well.
This site mentions an interesting use of the glory in religious art.