形容詞 deadpan:

1. deliberately impassive in manner
   同義詞：expressionless, impassive, poker-faced, unexpressive

副詞 deadpan:

1. without betraying any feeling

1. Deadpan delivery of the joke.
   用冷淡的表情講笑話
2. Some people do not catch his deadpan humor, that make it even funny.
   有些人不能了解他那種無表情的幽默，因此更有趣。

dead.pan

n.（名詞）
A blank, expressionless face.
冷面孔：茫然的、毫無表情的臉
A person, especially a performer, who has or assumes a blank expression.
面無表情的人，冷面演員：帶有或假裝出漠然表情的人，尤指演員
adj.（形容詞）
Impassively matter-of-fact, as in style, behavior, or expression:
表情冷淡的：泠漠乏味的，如在形式、行為或表情上：
例句：
deadpan delivery of the joke.
用冷淡的表情講笑話

adv.（副詞）
With a blank, expressionless face.
冷若冰霜的：以漠然的、毫無表情的面孔的
v.（動詞）
dead.panned,dead.pan.ning,dead.pans
v.tr.（及物動詞）
To express in an impassive, matter-of-fact way.
面無表情地：冷淡地、不帶感情地表達
v.intr.（不及物動詞）
To express oneself in an impassive, matter-of-fact way.
面無表情地表達：以冷淡的不帶感情的方式來表達自己