Radius.
Chat with our AI personalities
the single form of radii is radius
The singular form of a word is the form which applies only to one object, place, concept, animal, or person. For nouns, the singular form is usually the form which does not end in S. On verbs, the singular form usually ends in an S. Of course, for many words, another word is used instead, like using they as the plural form of he or she. The word they does not end in S.
The singular noun is guess; the plural form is guesses.
The singular form for the plural noun indices is index.
The singular noun is proof.The word proof is also a verb and an adjective.