nimbus, in art, the luminous disk or circle or other indication of light around the head of a sacred personage. It was used in Buddhist and other Asian art and by the early Greeks and Romans to designate gods and heroes and appeared in Christian art in the 5th cent. Although usually a circle or disk, the nimbus has various forms—triangular for God the Father; a circle with a cross for Jesus; a square for a living person; a disk or circle for a saint, with sometimes a band of small stars for the Virgin Mary. In stained glass Jesus and the Virgin were often represented surrounded by an ovoid light called a vesica piscis [Lat.,=fish bladder] (see iconography). The square form was symbolic of the material world; the circle symbolized spiritual perfection and eternal blessedness; and the triangle represented eternity and the Trinity. The nimbus is usually of gold and may have a clearly defined outline or the light may be diffused, radiating from the head in lines that melt into the picture. The term aureole may denote a crown or radiance around the head or it may be an oval used as a background for the whole body. When nimbus and aureole are combined for one figure, the illumination is called a glory. An almond-shaped glory is a mandorla. Halo is a nontechnical term to denote either a disk behind the head or a circle surrounding it.

nimbus, in meteorology, low, dark, formless cloud covering the entire sky, from which rain or snow is steadily falling. The term is usually applied to any cloud from which rain descends. Modifications are cumulonimbus, fractonimbus (ragged, broken nimbus), and nimbostratus.