frivolous

形容词 frivolous:

1. not serious in content or attitude or behavior

1. If I could intrude a note of seriousness into this frivolous conversation ...
   我真想说一句，叫他们谈话放严肃些 ...
2. I think there is a kernel of truth in these otherwise frivolous comments.
   我认为在这些本来是无关紧要的评论中含有一定的真实性。
3. At 18, he's still rather frivolous and needs to grow up.
   他到了十八岁仍然很不懂事，很不成熟。
4. She thought that reading romantic novels was a frivolous way of spending her time.
   她认为看浪漫小说是虚度时光。

friv.o.lous

adj.（形容词）
Unworthy of serious attention; trivial:
无关紧要的：不值得认真注意；不重要的：
例句：
a frivolous novel.
一部无关紧要的小说

Inappropriately silly:
轻率的：
例句：
a frivolous purchase.
轻率购买的东西

来源：
Middle English
中古英语
probably from Latin frovolus [of little value]
可能源自 拉丁语 frovolus [价值很小的]
probably from fri3re [to crumble]
可能源自 fri3re [弄成碎屑]

【引伸】
friv.olously
adv.（副词）
friv.olousness
n.（名词）