Yonder means over there, at some distance but within sight. When someone points and says “yonder mountain,” they're indicating a mountain you can see in the distance. A farmer might tell you the barn is down yonder, meaning it's that way, far enough that you'd need to walk a bit to reach it.

The word has an old-fashioned, rural feeling to it. You'll find it in classic stories and folk songs more often than in everyday conversation today. In The Wizard of Oz, when Dorothy sings about somewhere “over the rainbow,” she's describing a place similar to what older speakers might call “way out yonder.”

Yonder suggests something beyond immediate reach but not impossibly far. It's more specific than “over there” because it usually means something you can actually see or point to. You wouldn't say “yonder China” if you're in Kansas, but you might say “yonder hill” for one you can see from your porch.

The word adds a sense of space and distance to descriptions. When a character in a Western novel says “There's trouble yonder,” they're pointing to something visible in the distance while painting a picture of wide-open spaces where distant things still matter.