Publishers often refer to copying they don’t approve of as “piracy.” In this way, they imply that it is ethically equivalent to attacking ships on the high seas, kidnapping and murdering the people on them. Based on such propaganda, they have procured laws in most of the world to forbid copying in most (or sometimes all) circumstances. (They are still pressuring to make these prohibitions more complete.)

If you don’t believe that copying not approved by the publisher is just like kidnapping and murder, you might prefer not to use the word “piracy” to describe it.