/ pəˈrɪmɪtə(r); NAmE / noun
1.
the outside edge of an area of land :
Guards patrol the perimeter of the estate.
a perimeter fence / track / wall
2.
( mathematics ) the total length of the outside edge of an area or a shape
—compare circumference
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WORD ORIGIN
late Middle English : via Latin from Greek perimetros , based on peri- around + metron measure.