impassive

形容词 impassive:

1. having or revealing little emotion or sensibility; not easily aroused or excited
   同义词：stolid
2. deliberately impassive in manner
   同义词：deadpan, expressionless, poker-faced, unexpressive

im.pas.sive

adj.（形容词）
Devoid of or not subject to emotion.
无感情的：缺乏感情的或无动于衷的
Revealing no emotion; expressionless.
不流露情感的；冷漠的
Incapable of physical sensation.
无知觉的：缺乏身体感觉能力的
Motionless; still.
不动的；静止的

来源：
in-
in-
passive [suffering (obsolete)]
passive[受难的（废语）]

【引伸】
impas.sively
adv.（副词）
impas.siveness 或
im.passiv.ity
n.（名词）