The aureola, when enveloping the whole body, generally appears oval or elliptical in form, but occasionally depicted as circular, vesica piscis, or quatrefoil. When it appears merely as a luminous disk round the head, it is called specifically a "halo" or "nimbus", while the combination of nimbus and aureole is called a "glory". The strict distinction between nimbus and aureole is not commonly maintained, and the latter term is most frequently used to denote the radiance round the heads of saints, angels or Persons of the Trinity.