a tall mountain, especially one with a rough and rocky terrain and/or a snowcapped peak, or something that suggests such a mountain in size/height or unevenness;
e.g. They saw the alp on the horizon, its peak gleaming white with snow.
(noun)
in Switzerland, an area on/in the side of a mountain that has green pastures;
e.g. The cows were grazing in an alp near the mountain village.