A potrero is a long mesa that at one end slopes upward to higher terrain. This landform commonly occurs on the flanks of a mountain, as part of a dissected plateau.
A loan word from Spanish language, potrero is in current use in the southwestern United States, where it is sometimes translated as "tongue of land" and "enclosed piece of pasture land". In Spanish language, however, the "tongue of land" sense is archaic.
Also archaic is the related sense of potrero referring to someone who wrangles young horses (potros in Spanish) kept as breeding stock (not saddle or pack stock). In Spanish, the usual sense of potrero now refers to any land (such as a ranch, open range, or community pasture) where such horses are kept.
Notable examples of potreros include some of the many mesas of the Pajarito Plateau near Santa Fe, New Mexico (United States). Historically, these potreros were used as winter pasture for livestock (horses, sheep, and cattle) that were driven to and from lush summer pastures in the high grass valleys (valles) of the Valles Caldera. Today, these potreros are used in this manner by a large herd of elk. These potreros are natural enclosures, with only one principal exit: the narrow connection to higher land.
In Spain a potrero is common land in poor condition.