imperturbable /ˌɪmpɜːˈtɜːbəbəl/

• 1. 

  ADJ If you describe someone as imperturbable, you mean that they remain calm, even in disturbing or dangerous situations. 沉着的; 冷静的 [书面]

  例：

  Thomas, of course, was cool and aloof and imperturbable.

  当然，托马斯冷静、超脱且遇事沉着。