Add or Change Field Word

Hi. You have a great product. Thanks for making it available. It's helped me out immeasurably.

I'm curious to know if there is a way to edit or change the name of any of the intended Fields. I am in the process of organizing a massive library of music into playlists and want to group them a particular way. So in addition to "Artist/Title/Album" etc, I'd like to know if it's possible to add a new field or to change the name of an existing field. I've tried it in the Customize Columns section, but this seems to only apply to the way the information is displayed on my computer.

Any cues or clues?

Thank you~!