When something borders something else, it is said to abut it. The term is often used in real estate to refer to a lot line. Wouldn’t it be nice to have your back yard abut a forest preserve or park?
The Old French word but meant "end" — think of "butt" for a crude way to remember that! — and it was joined to a-, from the Latin ad- "near to." The result was abuter, which meant "to touch at an end." The word eventually became abouter, meaning "to join at the ends, or border on." The idea of abut suggesting a common boundary comes from the late Middle English, and today we use the word when anything touches something else.