An expanse is a wide, open area that stretches out far in front of you. When you stand at the edge of the ocean and look out at miles and miles of water reaching toward the horizon, you're looking at an expanse. When pioneers crossed America in covered wagons, they traveled through vast expanses of prairie where grass stretched endlessly in every direction.

The word emphasizes both size and openness. A crowded city isn't an expanse, even if it's large, because buildings fill up the space. But a desert, a wheat field in Kansas, or the night sky are all expanses because they feel open and unbroken. When astronauts describe space, they often talk about the expanse surrounding Earth, that enormous emptiness dotted with distant stars.

You can also use expanse for smaller areas when you want to emphasize how open they feel. A large frozen lake might be described as an expanse of ice. The word carries a sense of freedom and possibility, but sometimes loneliness too. Standing before a great expanse, you might feel small but also amazed at how much world there is to explore.