Ghyll is a word that refers to a narrow, steep-sided ravine or valley, often with a running stream or waterfall. Some synonyms for the word ghyll include gorge, ravine, canyon, chasm, and crevasse. Other words that can be used synonymously with ghyll include clough, coomb, defile, and gulch. These words all refer to a similar type of natural feature, but may be more commonly used in different regions or contexts. Whether you're hiking through a ghyll or exploring a canyon, the natural beauty and rugged terrain of these formations are sure to impress.