Entry 1 sense Webster, 1913 Cumu-cirro-stratus /(k?`m?-s?r`r?-str?"t?s)/ · Cu·mu-cir·ro-stra·tus · IPA 01 n. Nimbus, or rain cloud. See Nimbus, and Cloud. 1. Nimbus, or rain cloud. See Nimbus, and Cloud.(Meteor.) See: Nimbus, Cloud