You may attempt to influence behavior and ethics by redefining the meanings of words, or by confusing one meaning of a word with another, but I can't guarantee it will be successful.
If I were to "pirate" an entertainment file, I would not alter my self-image to believe that I am now "a thief", just because you're quoting dictionary definitions at me. I may still feel vaguely guilty about it, but nowhere near the level of guilt I might feel by walking over to my neighbor's driveway and stealing their car, even though the open-market value of the car may be only $5k, and the open-market value of the recording may be $5M.
This difference arises because when I copy something, I do not deprive the person in possession of the use of it. If I steal, I do. The concept of dispossession is fundamental to the concept of theft. When I take your thing, you no longer have it. When I copy your thing, we both have it. If you are then put out because I am no longer motivated to rent your thing, that's the result of your improper assumption that the idea of the thing belonged to you exclusively.
When "theft" moves from the physical to the intangible, it becomes plagiarism or counterfeiting. It is a greater sin to cut out the credit scroll from the end of a movie than to copy it without paying. It is a greater sin to copy the maker's mark than to copy the design it marks.
I am not the sort to lie to myself to influence my own state of mind. Things are what they are, and if that state cannot be conveyed effectively with words, then the language is at fault. The words must change, rather than my mental model of reality. If you cannot separate in your mind the definition of "piracy" that concerns intangible property from the definition of "stealing" that concerns tangible objects, I would suggest using instead a term that is more descriptive, and not quite so ambiguous, such as "copyright infringement". If one cannot be a "pirate" without being a thief, then copyright infringers will simply cease to be "pirates".
You can't change reality by altering the description of reality. If you perfectly duplicate a copyright-protected file in a manner not allowed by fair use or by an implicit or explicit license granted by the privileged holder of the copyright, the holder is neither dispossessed of their file, nor deprived of any reputation benefit which may be associated with their control of the copyright. Copyright infringement is therefore not theft. If we cannot agree on what words mean, we cannot meaningfully communicate. And if someone is changing the meanings of their words mid-conversation, that might be perceived as dishonest communication.