General terms:
* Open land: This is a neutral term, simply meaning land that is not enclosed.
* Unenclosed land: This is a more formal way of saying "open land."
* Unbounded land: This suggests a vast expanse of land with no clear boundaries.
More specific terms:
* Pasture: This implies land used for grazing animals.
* Common land: This refers to land shared by a community.
* Wilderness: This suggests undeveloped, wild land.
* Prairie: This specifically refers to grasslands.
* Heath: This refers to open land covered in low-growing shrubs and grasses.
* Moor: This refers to open, boggy land.
Figurative terms:
* Free range: This suggests land where animals can roam freely.
* The wild: This is a poetic term for untamed, unfenced land.
The best word to use will depend on the specific meaning you want to convey.