[zmgsabst]

A tidally locked satellite rotates: one rotation per orbit.

[this_was_posted]

unless the body it rotates around rotates at the exact same speed around another body in the opposite direction

[jacquesm]

Then it still rotates.

[throwaway290]

It can only rotate relative to an arbitrary point, not in some objective absolute sense. Here it does not rotate relative to chosen point.

[jacquesm]

Something about privileged reference frames...

[throwaway290]

But what's the alternative, right?