adverb
horizontally; flat
Describes something lying flat or oriented horizontally, often in contrast to vertical (縦に).
本を横に置いてください。
Please place the book horizontally.
彼は疲れてベッドに横になった。
He was tired and lay down flat on the bed.
adverb
Used for movement or orientation that is lateral, across, or to the side, often implying a direction perpendicular to the main axis.
車が横に並んで駐車している。
The cars are parked side by side.
彼は横に動いて道をあけた。
He moved sideways to make way.