n.[U]

1. 嚴肅性
   The reader who does not detect the seriousness under the lightness often misreads him.

   沒有意識到輕鬆掩蓋下的嚴肅性的讀者常常會誤解他。

2. 認真；當真
   Jack's countenance assumed an air of seriousness.

   捷克裝出認真的表情。

3. 嚴重性
   the seriousness of an error

   錯誤的嚴重性