perpendicular

Meanings

1. 1adjectivenot comparablemathematics

   Meeting another line, surface, or direction at an exact right angle of ninety degrees.

   Grammar: Always followed by 'to' when naming the other line or surface: perpendicular to the wall.

   Patterns

   • perpendicular to something
   • a perpendicular line
   • two perpendicular walls

   Hold the ruler perpendicular to the line you are drawing.

   The two perpendicular roads cross at the town square.

2. 2adjectivenot comparableinformal

   Standing or pointing straight up and down rather than at a slope.

   Grammar: Informal use meaning simply 'vertical'; in technical writing prefer 'vertical' or 'at right angles'.

   Patterns

   • perpendicular to the ground
   • climb something perpendicular

   The path became almost perpendicular near the summit.

   Make sure the shelf brackets are perpendicular to the ground before drilling.

Common combinations

perpendicular to the wall

Position the bookshelf perpendicular to the wall to divide the room.

perpendicular lines

Perpendicular lines form four equal right angles where they cross.

mutually perpendicular

The three axes of the graph are mutually perpendicular.

perpendicular to the ground

The sapling should grow perpendicular to the ground, not leaning sideways.

Synonyms and how they differ

vertical

Vertical means straight up and down relative to the ground; perpendicular describes a right-angle relation to any given surface.

orthogonal

Orthogonal is the technical mathematics and engineering word for perpendicular; avoid it in everyday speech.

Opposites

Word family

perpendicular noun

A line or direction at right angles to another; used in geometry.

Commonly confused: perpendicular or parallel?

Practice

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