What does horizontally mean?
Horizontally is an adverb meaning in a direction parallel to the horizon, or with something lying flat rather than upright. It is used to describe movement, such as an aircraft traveling horizontally, objects arranged side by side, or a surface positioned flat. The related adjective horizontal can describe a line, position, plane, or orientation, while horizontally indicates the manner or direction of an action. Although formally part of the word “horizontally” belongs to the same Latin-derived family as horizon and horizontal, its everyday use is largely neutral. In technical writing, it may distinguish a direction or alignment from a vertical one; in general descriptions, it can simply mean “across” or “sideways.” The word is particularly useful when precision matters, as when discussing geometry, screen orientation, image composition, or the alignment of objects.
adverbIn or along a horizontal direction, especially parallel to the horizon. It can also describe something positioned flat rather than upright.
- In or along a direction parallel to the horizon.
- With the long axis or broad surface positioned flat rather than upright.
"The swimmer moved horizontally across the pool before rising toward the surface."
"The banner stretched horizontally across the entrance to the hall."
"Place the keyboard horizontally if you want the screen to display in landscape mode."
Horizontally shares its roots with horizon: both trace back to the ancient idea of a boundary separating the visible earth from the sky.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does horizontally come from?
Horizontally was formed in English by adding the adverbial suffix -ly to horizontal. The adjective horizontal comes through French from Latin horizontalis, a derivative of horizon; horizon itself comes from Latin and ultimately from the Greek horos, meaning boundary or limit. The same Greek root also underlies the family of English words connected with limits, horizons, and boundaries.
Related word forms
How horizontally is actually used
The word is formal but widely understood in ordinary, technical, and academic contexts. It is especially common in descriptions of movement, orientation, layouts, and geometry.
Easily confused with horizontally
Horizontal is an adjective or noun, whereas horizontally is the adverb describing the direction of an action or position.
Vertical means upright or at a right angle to the horizon, while horizontally means in a direction parallel to the horizon.