Lower berth, also known as a bunk or bed, is a sleeping accommodation that is found on trains, ships, and even buses. Some common synonyms for lower berth include a bunk bed, a sleeper, a cot, a berth, and a cabin. A bunk bed features two separate beds that are stacked on top of each other while a sleeper is a more comfortable version of a bunk bed, with amenities such as pillows, blankets, and curtains for privacy. Meanwhile, a cot is a simple mattress that is usually unfolded and placed on the ground, while a berth is an enclosed or private area for sleeping. Lastly, a cabin is a private room that usually contains a lower berth, a bathroom, and other amenities.