behind someone's back
US /bɪˈhaɪnd ˈsʌm.wʌnz bæk/
UK /bɪˈhaɪnd ˈsʌm.wʌnz bæk/
1.
背着某人, 在某人背后
without someone's knowledge or without telling them
:
•
I can't believe she talked about me behind my back.
我不敢相信她在我背后议论我。
•
They made the decision behind his back.
他们背着他做了这个决定。