cumu-cirro-stratus

from The Collaborative International Dictionary of English v.0.48

Cumu-cirro-stratus \Cu"mu-cir`ro-stra"tus\
   (k?`m?-s?r`r?-str?"t?s), n. (Meteor.)
   Nimbus, or rain cloud. See {Nimbus}, and {Cloud}.
   [1913 Webster]