The American Heritage Dictionary's definition of the word 'plot', found in Peter Brooks' magnificent Reading for the Plot:
1. (a) A small piece of ground, generally used for a specific purpose. (b) A measured area of land; lot.
2. A ground plan, as for a building; chart; diagram.
3. The series of events consisting of an outline of the action of a narrative or drama.
4. A secret plan to accomplish a hostile or illegal purpose; scheme.
As Brooks points out, "there may be a subterranean logic connecting these heterogeneous meanings."
Brooks blew me away when I first read Reading for the Plot 20+ years ago, in college. I've just picked the book up again, and it doesn't seem to have aged a bit. Well worth a read if you're through with the screenwriting gurus of the world and ready for something a little meatier.