According to Wikipedia, The term "filibuster" originates from the Dutch word for pirates!
Dutch pirates were known as kapers or vrijbuiters ("plunderers"), the latter combining the words vrij meaning free, buit meaning loot, and the ending -er meaning agent. The word vrijbuiter was corrupted into the English freebooters and French flibustiers. It came back into English as filibusters, who were not pirates, but adventurers involving themselves in Latin American revolutions and coups and then finally came to mean the disruptive parliamentary maneuver of talking without stopping.
-- Wikipedia article on Pirates
