behind somebody's back

behind (one's) back

In one's absence. The phrase typically suggests wrongdoing or deceit. I can't believe you were gossiping about me behind my back! Tom will be upset that we already made the decision behind his back.
See also: back, behind
Farlex Dictionary of Idioms.

behind somebody’s ˈback

without somebody knowing, especially because they would not like it: I feel guilty about going behind his back and complaining to the boss. People were often very rude about her behind her back. OPPOSITE: to somebody’s face
See also: back, behind
Farlex Partner Idioms Dictionary
See also:
  • behind (one's) back
  • behind back
  • behind someone's back
  • do something behind someone's back
  • go behind (one's) back
  • go behind back
  • go behind someone's back
  • burner
  • back burner
  • backburner
References in periodicals archive
STUNNING news last week, as it emerged that no journalist on Fleet Street has ever said one thing to somebody's face and another behind somebody's back.
Journalists are never two-faced
There is no way on earth that he would go behind somebody's back. That just isn't his style.
FOOTBALL: TWO LITTLE BHOYS; Burns backs childhood pal to be a Firhill smash