지면이나 수평선과 평행하게, 또는 가로 방향으로.
In a position or direction parallel to the plane of the horizon; flat or level.
예문:
"The monitor can be rotated to display images either vertically or horizontally."
"The layers of rock were deposited horizontally over millions of years."
"Please stack the books horizontally to prevent the spines from warping."