密みつ雲うん

noun

dense clouds; overcast

Describes a sky thickly covered with clouds; somewhat literary or formal in tone.

• 空そらは密みつ雲うんに覆おおわれ、今いまにも雨あめが降ふり出だしそうだった。

  The sky was covered with dense clouds, looking as if it might start raining at any moment.