1911 Encyclopædia Britannica/Bilbo

BILBO (from the Spanish town Bilbao, formerly called in England “Bilboa,” and famous, like Toledo, for its sword-blades), in the earliest English use, a sword, especially one of superior temper. In the plural form (as in Shakespeare’s phrase “methought I lay worse than the mutines in the bilboes”) it meant the irons into which offenders were put on board ship.