Horizontal
Definition 1 of 4
Pro Tip 1/3
Visual Imagery
Imagine a flat surface or line running left to right, like lying down. She drew a horizontal line on the paper.
Pro Tip 2/3
Not Vertical
Remember that 'horizontal' is the opposite of 'vertical', which goes up and down. The shelves were installed horizontally, not vertically.
Pro Tip 3/3
Aligned with Horizon
Think of lying back to gaze at the sky; the line where earth meets sky is horizontal. At sunset, the horizontal glow was breathtaking.