# “Rotate about” vs. “rotate around”

Is there a difference in meaning between

This operation rotates the object about the axis defined by ...

and

This operation rotates the object around the axis defined by ...

(e.g. in the context of a graphical user interface)?

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About and around are synonymous in this context; they are both valid and mean the same thing.

Ngrams shows us that rotate has been more commonly used with about, though in later years the two options seem to have become more equivalent in terms of popularity:

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I think "About and around are synonymous in this context" isn't true. The phrasing "rotates ... about the axis" is well-understood and well-defined mathematical terminology with specific meaning; the phrasing "rotates ... around the axis" is not, and as such may introduce doubt in the mind of any careful reader regarding what is meant. – jwpat7 Oct 18 '11 at 23:34
Could you perhaps explain why rotates ... around the axis confuses the meaning? I've heard and seen it a lot. – Daniel Oct 19 '11 at 0:08
What I would rather do is delete my previous comment :) rather than try to substantiate it. However, I find upon clicking on quotations at the given ngrams link (on the first pages of them, at least) that uses of "rotate about" seem precise, while uses of "rotate around" (except the first link) are not; eg: "You can allow the user to rotate around any single axis or pair of axes" (user rotates? or axis rotates?) and "the heavens are round everywhere and rotate around themselves" (how?). – jwpat7 Oct 19 '11 at 0:56

I'm not really sure if this is a well-defined and widely accepted difference, but to me, "Rotate about" implies that the object is spinning in place (i.e. the defined axis passes through the center of the object in question, or at least through some internal point of the object), while "rotate around" implies that the object is orbiting an external point.

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Of course, when the axis is defined, the preposition makes little difference. – Daniel Oct 18 '11 at 19:25