<p><strong>Noun</strong></p><ul><li>plural: radii</li><li>a straight line extending from the center of a circle or sphere to the circumference or surface: The radius of a circle is half the diameter</li><li>the length of such a line</li><li>any radial or radiating part</li><li>a circular area having an extent determined by the length of the radius from a given or specified central point: every house within a radius of 50 miles</li><li>a field or range of operation or influence</li><li>extent of possible operation, travel, etc., as under a single supply of fuel: the flying radius of an airplane</li><li>Anatomy: the bone of the forearm on the thumb side; compare ulna</li><li>Zoology: a corresponding bone in the forelimb of other vertebrates</li><li>Machinery (Now Rare): the throw of an eccentric wheel or cam</li><li>a rounded corner or edge on a machined or cast piece of metal</li><li>Entomology: one of the principal longitudinal veins in the anterior portion of the wing of an insect</li></ul>