Britannica Dictionary definition of RADIUS
[count]
1
technical
:
a straight line from the center of a circle or sphere to any point on the outer edge
2
:
an area that goes outward in all directions from a particular place
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The new museum is expected to draw people from a wide radius.
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More than 100,000 students live within a 10-mile radius of the university. [=within 10 miles of the university]
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There are three restaurants within a one-block radius of our apartment.
3
medical
:
the bone in the lower part of your arm on the same side as your thumb
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see picture at human