perimeter

/pəˈrɪmɪdər/

/peˈrɪmɪtə/

Other forms: perimeters

The noun perimeter refers to the border of an enclosed space. The perimeter of a house is its property line. For a country, it would be that country’s borders.

From Latin peri meaning “around” and metron meaning “measure,” a perimeter is basically a boundary of any kind, measuring around the shape. In mathematics, perimeter refers to the length of this boundary. In geometry class, you might be asked to calculate the perimeter of a polygon, which is the sum of the length of each side. You might also hear this word used by members of the military or a police force as in “secure the perimeter” or “the perimeter has been breached.” A basketball player that likes to shoot from the three point line is said to “operate on the perimeter.”

Definitions of perimeter

1. noun

   a line enclosing a plane area
   type of:

   line

   a length (straight or curved) without breadth or thickness; the trace of a moving point
2. noun

   the boundary line or the area immediately inside the boundary
   synonyms: border, margin

   types:

   lip

   either the outer margin or the inner margin of the aperture of a gastropod's shell

   type of:

   bound, boundary, edge

   a line determining the limits of an area
3. noun

   the size of something as given by the distance around it
   synonyms: circumference

   types:

   girth

   the distance around a person's body

   spread

   the expansion of a person's girth (especially at middle age)

   type of:

   size

   the physical magnitude of something (how big it is)