perpendicular

American  

[pur-puhn-dik-yuh-ler] / ˌpɜr pənˈdɪk yə lər /

adjective

1. vertical; straight up and down; upright.

   Synonyms:

   standing

2. Geometry. meeting a given line or surface at right angles.

3. maintaining a standing or upright position; standing up.

4. having a sharp pitch or slope; steep.

5. (initial capital letter) noting or pertaining to the last style of English Gothic architecture, prevailing from the late 14th through the early 16th century and characterized by the use of predominantly vertical tracery, an overall linear, shallow effect, and fine intricate stonework.

---

noun

1. a perpendicular line or plane.

2. an instrument for indicating the vertical line from any point.

3. an upright position.

4. a sharply pitched or precipitously steep mountain face.

5. moral virtue or uprightness; rectitude.

6. Nautical. either of two lines perpendicular to the keel line, base line, or designed water line of a vessel.

perpendicular British  

/ ˌpɜːpənˌdɪkjʊˈlærɪtɪ, ˌpɜːpənˈdɪkjʊlə /

adjective

1. Also: normal.  at right angles to a horizontal plane

2. denoting, relating to, or having the style of Gothic architecture used in England during the 14th and 15th centuries, characterized by tracery having vertical lines, a four-centred arch, and fan vaulting

3. upright; vertical

---

noun

1. geometry a line or plane perpendicular to another

2. any instrument used for indicating the vertical line through a given point

3. mountaineering a nearly vertical face

perpendicular Scientific  

/ pûr′pən-dĭk′yə-lər /

1. Intersecting at or forming a right angle or right angles.

---

1. A line or plane that is perpendicular to a given line or plane.

Related Words

See upright.

Other Word Forms

• nonperpendicular adjective
• nonperpendicularity noun
• nonperpendicularly adverb
• perpendicularity noun
• perpendicularly adverb
• perpendicularness noun
• unperpendicular adjective
• unperpendicularly adverb

Etymology

Origin of perpendicular

First recorded in 1350–1400; from Latin perpendiculāris “vertical,” equivalent to perpendicul(um) “plumb line” ( perpend ², -i-, -cule ² ) + -āris -ar ¹; replacing Middle English perpendiculer(e) (adjective and adverb), from Old French perpendiculiere

Explanation

Two lines that form a T are perpendicular to each other. They meet at a right angle. A person who is standing is perpendicular to the earth. Use perpendicular to describe lines, angles, and direction. In geometry a perpendicular angle is 90 degrees, a perfect L. On a compass, East and North are perpendicular to each other. The term can be used more generally to describe any steep angle. You might talk about a ski slope that is nearly perpendicular but that's impossible since gravity would make you fall off a 90-degree angle. But if it's close enough, no one's really measuring.

Example Sentences

The front door is easily visible from the road—but likely out of eye or camera sight from even the neighbors up the hill on perpendicular Cerrada Chica.

From The Wall Street Journal • Feb. 13, 2026

On Wednesday in Minnesota, 37-year-old Renee Nicole Good was in her car, perpendicular to traffic, during an Immigration and Customs Enforcement operation in Minneapolis.

From Slate • Jan. 10, 2026

The images revealed two separate gas flows moving in perpendicular directions -- a sign that the event involved multiple ejections interacting with each other.

From Science Daily • Dec. 31, 2025

With a forkball that looked as if it was dropping perpendicular to the ground, he struck out the first two batters he faced.

From Los Angeles Times • Oct. 2, 2025

I streamed the sea anchors— what was left of them—full open to keep us perpendicular to the waves, and I tripped them as soon as we began riding a crest.

From "Life of Pi" by Yann Martel

Related Words

• erect
• on end
• plumb