Thanks to languagehat for a wonderful link (he got it from aldiboronti at Wordorigins – afraid that always makes me think of Aldi) – a multilingual list of chess vocabulary (chess pieces, Schachfiguren) with an introduction discussing the various terms.
2018 update – that link is now dead- see comment by George L. – here is a new link, thanks to him:
bq. The rooks differ in many ways in different languages. The rook is a tower in many European languages (eg. Spanish and Portuguese torre, Finnish torni, French tour, Dutch toren), sometimes a large farm (Frisian stins), a ship (Russian lad’ja, transcribed also as ladya) or a wagon (Chinese ju, Estonian vanker).
bq. Until the new queen’s move was introduced in the 15th century the rook was the most powerful piece. Except for the castling the powers of the rook have been unchanged throughout the known history of chess.
But why is a rook a rook? The OED says it goes back to a Persian word whose meaning is doubtful.
Bishop is German Läufer (runner), but I didn’t know it was Turkish fil (elephant). Apparently that came from Persian pil, elephant or chess piece, which became fil in Arabic.