radii
The plural of "radius" is radii.
radius comes from Latin, and like many Latin nouns ending in -us it changes the ending to -i.
Meaning: the distance from the center of a circle to its edge, or a bone in the arm (noun)
How does it change in a sentence?
Use a plural verb with radii: the radii are. Because radii does not end in s, the possessive plural is radii's.
How do you pronounce it?
radius is pronounced /ˈɹeɪ.di.əs/.
What mistakes should you avoid?
radii, said RAY-dee-eye, is the usual plural in math and science. radiuses is also correct.
Did you know?
- Over time, borrowed words often take a regular English plural too: forums and stadiums are now more common than fora and stadia.
Examples in context
- The two circles have equal radii.Singular: The circles have the same radius.
- Both radii were broken.Singular: The radius was broken.
