Nimbus

Nimbus, in art, the halo or circle of rays round the head of a deity, angel, saint, or emperor. The pattern came to be varied; for instance, the nimbus of Christ contained a cross, of God a double triangle, while that of a living emperor was square. The term is often confused with aureola, the rays of which surround the whole figure, and with glory, which is properly a combination of aureola and nimbus.