Religious symbols are used to represent a faith or belief system, and can take many forms. The term RELIGIOUS SYMBOL can refer to the four solutions given in the crossword: HALO, CROSS, ICON, and IKON. A HALO is a circle of light that is often depicted around the head of a holy figure in religious art. The CROSS is one of the most widely recognized religious symbols, and is associated with Christianity. An ICON is a two-dimensional representation of a holy figure, while an ikon is a three-dimensional representation. Finally, Celtic crosses are a type of CROSS that combines a Christian CROSS with a circle, and are often used as a symbol of Irish heritage.