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stupid; foolish; idiotic; inane
fool; idiot; blockhead; half-wit
間抜けな失敗で笑われた。
I was laughed at for a foolish mistake.
間抜けに見えるがあの人は実は賢い。
He looks foolish, but he is actually smart.
間抜けなミスで大事な会議を台無しにしてしまった。
A stupid mistake ruined an important meeting.