When we say someone "shifted ground," we usually mean that they have changed their position or point of view on a particular topic. There are a number of synonyms we could use to express this idea, such as "changed tack," "altered stance," "revised opinion," "moved goalposts," "morphed perspective," or "evolved position." Each of these phrases offers a slightly different shade of meaning or connotation, but all of them convey the sense that the person in question has pivoted or adapted in some way. Whether you're writing an opinion piece, a news article, or a personal reflection, choosing the right synonym can help you convey your meaning more clearly and precisely.