noun (plural radii /-dɪʌɪ/ or radiuses)
- 2 Anatomy the thicker and shorter of the two bones in the human forearm. Compare with ulna.
verb (radiuses, radiusing, radiused)[with object] (often as adjective radiused)
late 16th century (in radius (sense 2 of the noun)): from Latin, literally 'staff, spoke, ray'
The plural of radius can be spelled either radii (as in the original Latin) or radiuses.