nim·bo·strat·us 
(nĭm′bō-strătəs, -strātəs)
(nĭm′bō-strătəs, -strātəs)n.
A low, gray, often dark cloud that precipitates rain, snow, or sleet.
[NIMB(US) + STRATUS.]
nimbostratus- cosmic microwave background radiation
- cosmic noise
- cosmic ray
- cosmic ray air shower
- cosmic string
- cosmid
- cosmo
- cosmo-
- cosmochemical
- cosmochemist
- cosmochemistry
- cosmogenic
- cosmogonic
- cosmogonical
- cosmogonically
- cosmogonist
- cosmogony
- cosmographer
- cosmographic
- cosmographical
- cosmographically
- cosmography
- cosmologic
- cosmological
- cosmological constant