Used about the way a government runs a country's economy: it spends less and tightens things for a while, then loosens and spends more, then tightens again. The picture is a driver who keeps pressing the brake and then the accelerator, over and over. It is almost always used before a noun — 'stop-go policies', 'stop-go economics', 'a stop-go approach' — and it is almost always a criticism. Nobody praises their own plan by calling it stop-go; you call someone else's plan that, meaning it has no steady direction and businesses cannot plan ahead. The word belongs mostly to British writing about the economy, especially about Britain in the 1950s-70s, and you meet it in newspapers and history books more than in speech. People also stretch it outside economics, to anything that keeps starting and stopping: stop-go traffic, a stop-go building project, stop-go funding for a school. That looser use is common and safe. There is no verb 'to stop-go'.