a cloud of a class characterized by a formless layer that is almost uniformly dark gray; a rain cloud of the layer type, of low altitude, usually below 8000 feet (2440 meters).
1932 (earlier use from late 19c. refers to different cloud types), from Modern Latin nimbus (see nimbus) + connecting element -o- + stratus (see stratus).
A dark, gray, mid-altitude cloud that often covers the entire sky and precipitates rain, snow, or sleet. Nimbostratus clouds generally form around 2,000 m (6,560 ft) but often extend to much higher and lower altitudes. See illustration at cloud.
