The word "gulley" refers to a narrow, steep-sided ravine, often formed by the erosion of water. Antonyms for this word include "hill," "mountain," "plateau," and "mesa," which are all characterized by height and elevation rather than a narrow, low-lying terrain. Other antonyms for "gulley" may include words such as "plain," "flatland," and "prairie," which are all characterized by their relatively even, open landscapes. Regardless of the antonym used, each term paints a vastly different picture of the natural landscape, highlighting the vast diversity of environments that can be found around the world.