名詞 nonchalance:

1. the trait of remaining calm and seeming not to care; a casual lack of concern
   同義詞：unconcern, indifference

1. He conceals his worries behind a mask of nonchalance.
   他裝作若無其事，藉以掩飾內心的不安。

non.cha.lance

n.（名詞）
Casual lack of concern:
冷漠的不關心的態(tài)度：
例句：
.The contemptuous nonchalance of her trailed hand irritated him.(Elizabeth Bowen)
.她的懶洋洋的手所顯示出的蔑視而又漠不關心的態(tài)度激怒了他.(伊麗莎白·鮑恩)