His main reason is that the French knew the piece only as an Alfil, not as a Fil. It should be noted that Murray rejects this etymology of the name fou, but his reasons don't stand up well. This led to the current French name for the piece, which is fou, meaning jester or fool. The French also played on the similarity in sound between fil and the French word fol, which is related to the English word fool. The French began calling it delfino, which suggested 'dauphin,' the French crown prince. Italians started calling it Alfiere, which meant flag-bearer. In trying to find some meaning in the name, Europeans often used similar sounding words in their own languages. When the names of Fil and Alfil reached Europe, they were meaningless to the Europeans. At some point, the Arabic definite article got prepended, giving the name Alfil, meaning the elephant. Persians called it Pil, the Persian word for elephant, and the Arabs modified this to Fil. The Bishop has its roots in an Indian piece called a Hasty or Gaja, which were both Indian words for elephant. This was part of an overall reform of the rules of Chess, making the game much faster. In the end of the middle ages, the slow Alfil was replaced in the game of chess by the Bishop.

But it is not a set of standards concerning what you must call pieces in newly invented games. The Piececlopedia is intended as a scholarly reference concerning the history and naming conventions of pieces used in Chess variants. Rules of Training Chess: Rook, Bishop, Queen moves.Rules of Rookheavy Chess and Bishopheavy Chess.

Chess pieces by name