Definition: the bounds of a physical or conceptual space
An ambit could be around a physical or geographic space. But it could also refer to the limits of knowledge or influence.
Why I Looked It Up
In a book about science, the author wrote about scientific agencies were discounted by the Trump administration:
[…] and moving its offices from the Old Executive Building, right next to the White House, tot he Siberia of rented quarters outside the White House ambit.
In this case, it might be referring to physical proximity to White House, or perhaps it’s referring to the sphere of influence to the administration, for which physical distance is a reasonable proxy.
Added on January 9, 2022
From The Constitution of Knowledge: A Defense of Truth:
First on talk radio, then on cable television, and eventually online, conservatives built a media counter-establishment. In some respects, that was a welcome development, diversifying the information supply and widening the ambit of received opinion.
Clearly, “ambit” in this case is a conceptual space, not a physical one.