In traditional Christian usage, a chapel is a building or part of a building enclosing an altar and intended for private worship. The word is derived from the cloak (Latin: capella) of Saint Martin, a famous relic and the special talisman of the French king. This cloak was kept by the king's clergy (Latin: capellani, hence chaplains) in a private church, which thus became known as the chapel. The term was then extended to other private royal churches and eventually to nonroyal structures.