What does perpendicularly mean?
Perpendicularly is an adverb meaning at a right angle, or at an angle of 90 degrees, to another line, plane, or direction. For example, a road that crosses another perpendicularly meets it at a right angle rather than at a slant. The word can also describe movement directly upward or downward, especially in technical or formal contexts. Figuratively, it means acting in a way that directly opposes or contradicts another course of action. Although relatively uncommon in everyday speech, perpendicularly is precise and useful in geometry, engineering, construction, and technical description. Its specialized meaning is shared by British and US English, while the figurative use tends to sound formal.
At an angle of 90 degrees to another line or surface; directly upward or downward.
"The support post is positioned perpendicularly to the floor."
This is the standard technical and mathematical sense.
Directly opposed to or contrary to another direction, course, or intention.
"The decision was made perpendicularly to the advice of the panel."
This figurative sense is relatively formal and less common than the geometric meaning.
Perpendicularly means exactly at 90 degrees: the mathematical idea of a perfect right angle made into an adverb.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does perpendicularly come from?
Perpendicularly comes from the Latin perpendere, meaning 'to weigh' or 'to hang down,' combined with the prefix per-, which could convey thoroughness or direction. Its development into the sense 'at right angles' reflects the idea of a plumb line or hanging weight, which naturally establishes a straight vertical direction. The related English adjective perpendicular and the noun perpendicularity continue this Latin inheritance.
Related word forms
How perpendicularly is actually used
The mathematical sense is precise and standard in both British and US English. The figurative sense, meaning directly opposed to a course of action, is less common but established.