What is Cloud ?
Cloud is (noun) 1. a mass of white or grey vapour floating in the air Do you think it’s going to rain? – Yes, look at those grey clouds. The plane was flying above the clouds. 2. on cloud nine very happy (informal.) They were on cloud nine when she won the lottery. under a cloud suspected of having done something wrong He was under a cloud for some time after the thefts were discovered. 3. a mass of smoke floating in the air Clouds of smoke poured out of the burning shop.
source: Easier English, Student Dictionary Upper Intermediate Level