fifth wheel

US /ˌfɪfθ ˈwiːl/
UK /ˌfɪfθ ˈwiːl/
"fifth wheel" picture
1.

多餘的人, 累贅

a person who is in a situation where they are not needed or are superfluous

:
I felt like a fifth wheel on their romantic dinner.
在他們的浪漫晚餐上,我感覺自己像個多餘的人
When they started talking about their inside jokes, I knew I was the fifth wheel.
當他們開始談論他們的內部笑話時,我知道我是個多餘的人