Firienfeld was how the Rohirrim called the flat upland of Dunharrow; a large grassy area for the encampment of soldiers and refuge-seekers.
Firien represents Old English firgen "mountain". -feld, means "field" and Tolkien left it unmodernised; the Firienfield of the Index is in error.
- ↑ J.R.R. Tolkien, "Nomenclature of The Lord of the Rings" in Wayne G. Hammond and Christina Scull (eds), The Lord of the Rings: A Reader's Companion