filibuster [L18th] A filibuster was a 16th-century pirate or privateer. The word links a number of languages, reaching back through Spanish and French to vrijbuiter, from vrij ‘free’ and buit ‘booty’, a Dutch word from which we also get freebooter [L16th]. In the 19th century the Spanish filibustero was used for American adventurers who stirred up revolution in Central and South America, and filibuster came to be used in the USA to describe behaviour in congressional debates intended to sabotage proceedings. From this we get the current sense [L19th], ‘a very long speech made in Parliament to prevent the passing of a new law’ or the making of such a one [M19th].