Perimeter

How to spell perimeter

9 letters · 4 syllables

How to pronounce perimeter

Say the part in capitals loudest.

What does perimeter mean?

1. nounThe continuous line or total distance around the edge of a two-dimensional shape or area.
2. nounThe outer boundary or edge of an area, especially one that is guarded or fortified.

Perimeter in a sentence

• The pupils measured the perimeter of the rectangular playing field.

• Security guards patrolled the perimeter of the warehouse all night.

• To find the perimeter of a square, add the lengths of all four sides.

• The army established a defensive perimeter around the camp.

Where does perimeter come from?

Language of origin: Greek

This word comes from the Greek perimetros, meaning 'the measurement around something', built from peri 'around' and metron 'measure'. The Greek term passed into Latin as perimetros and was used by mathematicians for the total length of the boundary of a flat shape. English adopted it in the early 1400s, chiefly as a technical term in geometry. Over time the meaning broadened from the measured distance around a figure to the boundary or outer edge itself, which is why we now speak of the perimeter of a building or a security perimeter. The metron root sits inside many measuring words such as 'thermometer' and 'diameter', and the peri- prefix (the same one in 'periscope' and 'perimeter') is the key to remembering that the single -r- belongs to peri- while the rest spells out 'meter'.

How the word is built

• peri- (around)
• meter (from Greek metron: measure)