* Most commonly, it means "cairn," a heap of stones. This is often used to mark a grave, a boundary, or a significant place.
* It can also mean "heap" or "pile" in a more general sense. For example, a "carn o ddaear" (carn of earth) would be a mound of dirt.
* Less commonly, it can mean "peak" or "summit." This usage is more poetic or descriptive.
It's important to consider the context of the word to understand its intended meaning.