perpendicular

American  

[pur-puhn-dik-yuh-ler] / ˌpɜr pənˈdɪk jə 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

• perpendiculars
  plural

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.

Synonym Usage

See upright.

Other Word Forms

Derived Forms

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

Inflected Forms

Nouns

• perpendiculars
  plural

Etymology

Origin of perpendicular

First recorded in 1350–1400; from Latin perpendiculāris “vertical,” equivalent to perpendicul(um) “plumb line” ( see 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

See Examples For:

perpendicular perpendiculars

Hammerheads stand out from other shark species by the distinctive shape of their heads, which stick out perpendicular to their bodies in the shape of, well, a hammer.

From Los Angeles Times ● Aug. 15, 2026

His awkward angle, coming from beyond the perpendicular, with the ability to move the ball away from right-handers makes him very challenging for a batter to line up.

From BBC ● Jun. 2, 2026

In the end, some 8,000 small seismic events were induced along the targeted fault, but also, surprisingly, along other faults running perpendicular to the main one, sparking local magnitudes ranging from -5 to -0.14.

From Barron's ● May 11, 2026

Tévoédjrè stood beside an armored vehicle on the perpendicular street, positioned between the oncoming column and Talon’s residence.

From The Wall Street Journal ● Mar. 12, 2026

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

She uses a measuring stick to set the plants an equal distance apart, and as the beds are connected, the effect is one of perfectly aligned diagonals and perpendiculars.

From New York Times ● Jul. 1, 2010

Under those glorious perpendiculars . . . this gesticulating gigolo in gilt.

From Time Magazine Archive

It will be noticed that the above problems require the erecting of perpendiculars, the bisecting of angles, and the application of the propositions on tangents.

From The Teaching of Geometry by David Eugene Smith

The rate of whole inscripts doth follow, the which whole one diameter doth make: 13 Inscripts are equall distant from the center, unto which the perpendiculars from the center are equall 4 d iij.

From The Way To Geometry by William Bedwell

Measure from A to B by holding the tape taut and level, dropping perpendiculars when necessary by means of the plumb line, as shown in the figure.

From The Teaching of Geometry by David Eugene Smith

Related Words

• erect
• on end
• plumb