radius

word

/ˈɹeɪdiəs/
RAY-dee-us
/ɹˈeɪdɪəs/
RAY-dee-us

Definition

The straight line from the center of a circle to its edge. It can also refer to one of the two main bones in the forearm.

Usage & Nuances

Mathematics and geometry: always refers to the distance from center to edge, not edge to edge (which is 'diameter'). In anatomy, 'radius' is a bone in the forearm, located on the same side as the thumb. Don't confuse with 'diameter' or 'radius' in physics (sometimes means range or area).

Example Sentences

The radius of this circle is 5 centimeters.

basic

My teacher explained what the radius means in geometry class.

basic

The store delivers within a five-mile radius.

natural

Doctors checked the X-ray for any damage to the radius after her fall.

natural

She broke her radius while skating last year.

basic

You can find the area of a circle if you know its radius.

natural