When something is overarching, it does not sit in one corner of a plan, a story, or a life. It stretches over the whole thing, like a wide arch over a path, and it touches or shapes every part. An overarching goal is the one big aim that all the smaller jobs are meant to serve. An overarching theme in a book is the idea that keeps coming back in every chapter, not a detail that appears once. You will hear this word in school, in the news, and at work. It sounds a little formal, a little like an essay, but people do say it out loud. Though actually, speakers often reach for it when they only mean “main” or “overall”. That is close, but the extra picture is coverage: not just the biggest piece, but the one that includes or steers all the others. We almost never use it now for a real arch in the sky; it lives in ideas, rules, and stories.