perpendicular

Definition

Perpendicular lines are lines that meet at a right angle. This means that the two lines form a 90-degree angle. You can think of a right angle as a corner of a square or a rectangle.

Here is a picture of two perpendicular lines:

You can also use a protractor to measure the angle between two lines. If the angle measures 90 degrees, then the lines are perpendicular.

How can the word be used?

The ladder was leaning against the wall at a perpendicular angle.

Different forms of the word

Adjective:

perpendicular (at right angles to something else).
perpendicularity (the state of being perpendicular).

Noun:

perpendicular (a line or plane that is perpendicular to something else).

Etymology

The word "perpendicular" comes from the Latin word "perpendiculum", which means "plumb line". The first recorded use of the word "perpendicular" in English was in the 14th century.

Question

What does perpendicular mean?