[informal] stupid

愚蠢的:

What a dumb question.

多么愚蠢的问题。

a bunch of dumb kids

一帮笨孩子

'What is it?' I asked, playing dumb (=pretending to be stupid) .

“那是什么？”我装傻问道。

She's no dumb blonde (=a pretty woman with blonde hair who seems stupid) .

她可不是那种没有头脑的金发女郎。

unable to speak, because you are angry, surprised, shocked etc

〔因愤怒、惊讶、震惊等而〕说不出话的:

He stared at the burnt-out car in dumb disbelief.

他望着烧毁的汽车，吃惊得说不出话来。

She was struck dumb with terror.

她恐惧得说不出话来。

[old-fashioned] someone who is dumb is not able to speak at all. Many people think that this use is offensive

〔人〕哑的〔许多人认为此词具有冒犯性〕;

dumb luck, [informal] something good that happens in an unexpected way, especially when it is not deserved

纯粹是运气〔尤指不配得到〕:

It was just dumb luck that we found the place at all.

我们发现那地方纯粹是靠运气。

dumb animals / creatures, used to talk about animals when you want to emphasize that humans often treat them badly and they cannot protect themselves

不会说话的动物/生物〔用于强调人们常虐待动物，而它们却无法保护自己〕

For a few seconds she gazed dumbly at him.

有几秒钟她呆呆地凝视着他。