形容詞 frivolous:

1. not serious in content or attitude or behavior

1. If I could intrude a note of seriousness into this frivolous conversation ...
   我真想說一句，叫他們談話放嚴肅些 ...
2. I think there is a kernel of truth in these otherwise frivolous comments.
   我認為在這些本來是無關緊要的評論中含有一定的真實性。
3. At 18, he's still rather frivolous and needs to grow up.
   他到了十八歲仍然很不懂事，很不成熟。
4. She thought that reading romantic novels was a frivolous way of spending her time.
   她認為看浪漫小說是虛度時光。

friv.o.lous

adj.（形容詞）
Unworthy of serious attention; trivial:
無關緊要的：不值得認真注意；不重要的：
例句：
a frivolous novel.
一部無關緊要的小說

Inappropriately silly:
輕率的：
例句：
a frivolous purchase.
輕率購買的東西

來源：
Middle English
中古英語
probably from Latin frovolus [of little value]
可能源自 拉丁語 frovolus [價值很小的]
probably from fri3re [to crumble]
可能源自 fri3re [弄成碎屑]

【引伸】
friv.olously
adv.（副詞）
friv.olousness
n.（名詞）