Thank you - you're quite right. I should have written, "copying isn't theft".

It shouldn't be a surprise to you that words can have more than one meaning.

This one is by design.

'Piracy' was defined as copyright violation by the copyright holders, not by general usage.

Therefore, we should fight that usage, just to compensate the balance.

I follow but disagree. The world's largest and most successful torrent site calls itself The Pirate Bay. There are political "Pirate Parties" in Canada and Sweden. It may have been a pejorative label initially, but file sharers have "owned" the name and made it their own.

That's exactly how language is defined; by popular usage, not by design.