/ˌkju:mjʊləʊˈnɪmbəs ||; ˌkjumjəloˈnɪmbəs/noun [U] (technical术语) a type of cloud that forms a large very high mass, with a flat base at a fairly low level, and often a flat top. It is seen, for example, during THUNDERSTORMS 积雨云 ☞picture at cloud 见cloud插图