Related Clues:
- The line y = 0, in math
- Part of a plane
- Plane part
- Horizontal line on a graph
- Graph line
- Vertical graph component
- Geometric vertical
- Bottom line?
- Graph vertical
- Horizontal base of a coordinate system
- Vertical line on a graph
- Plotter's line, perhaps
- Cartesian coordinate line
- Graph component
- Side of a Cartesian quadrant