MTN stands for Mountain, which is a large landform that rises above the surrounding land in a limited area. The crossword solutions ELEV (4 letters), ALT (3 letters), and HGT (3 letters) refer to three different statistics related to mountains. ELEV stands for elevation, which is the height of a mountain above sea level. ALT stands for altitude, which is the height of a mountain above the ground. HGT stands for height, which is the vertical distance between the base and the summit of a mountain.