Is there, or has there ever been, an unambiguous word for "the leftmost extreme" or "the rightmost extreme"? Such words exist for the other two dimensions.
Imagine you are floating in a cube in space.
- You can go up until you hit the top.
- You can go down until you hit the bottom.
- You can go forward until you hit the front.
- You can go backward until you hit the (back/rear).
- You can go left until you hit the _______?
- You can go right until you hit the _______?