"Piracy" essentially means armed robbery and murder on the high seas. The recent abuse of the term to refer to unauthorized duplication is idiotic.
Actually, this modern usage of the term "piracy" in relation to media probably stems from the 1970s pirate radio stations which broadcast alternative songs by radio from ships offshore in international waters just outside the legal limits of the country concerned. This allowed them to (a) broadcast what they liked and not what the media machines wanted and (b) to avoid certain "costs"... Needless to say, the media machines got their way. Here is one of several sites that describe those halcyon days. http://www.offshoreradio.co.uk/
He who has but four and spends five has no need for a wallet.