cloud
klaʊd
noun
a visible mass of condensed watery vapour floating in the atmosphere, typically high above the general level of the ground.
the sun had disappeared behind a cloud
verb
(of the sky) become overcast or gloomy.
the blue skies clouded over abruptly
become cloudy,cloud over,become overcast,become gloomy,grow dim,lour,blacken,darken,dim