For instance

Curvature radius


Radius of curvature

Is there difference between both? When I need to use "of" in this kind of word?

Another example

Computing time


Time of computing

Are they the same? I already saw the both, in academic books, and I'm confused with it. In my language always it is used "of".

Thank you in advance.

2 Answers 2


I think "radius of curvature" is how that idea is usually expressed, not "curvature radius", so it would be best to stick to using "of".

As to "computing time" and "time of computing", the phrase is ambiguous. I would think "time of computing" would be the time at which the computing occurred, while "computing time" suggests elapsed time during the computation; but without context or custom to disambiguate, it would be better to express the ideas more precisely.


Yes, they are the same. The ones without "of" are more of the name of the quantity, the ones with "of" is a description of the quantity. Of is used to show a relation or a possession between an object and a subject. Please refer to the Oxford's Online Dictionary for reference. You can always get the correct usage there.

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