: going straight up or to the side at a 90 degree angle from another line or surface
a perpendicular line
She lives on the street that is perpendicular to mine.
a perpendicular cliff [=a cliff that goes straight up]
Cite this Entry
“Perpendicular.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/perpendicular. Accessed 22 Apr. 2026.
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