What word do you use when someone unrightfully gains possession of something that isn’t theirs?

Btw a lot of words in English have multiple meanings, and transform meaning over time, which can be confusing sometimes. For example, in baseball you steal a base, which was being protected by the other team, but you don’t remove the base from the field and run off with it.

I think steal works better than copy here, more accurately conveying meaning and intention, and unjust access.