Other forms: aborted; aborting; aborts
To abort something is to end it. When something is aborted, it's finished.
In a movie, you may have seen people on some kind of mission yelling "Abort! Abort!" That means "Stop!" When you abort a plan or activity, you're ending it, usually prematurely. If you abort a dinner, you cancel it in the middle. If the police abort a raid, they stop it after it has already begun. A writer could abort a novel after writing a chapter or two. You can't abort something that hasn't been started: that's more like canceling or postponing.