From Longman Dictionary of Contemporary Englishin concert (with somebody)in concert (with somebody)a) formal people who do something in concert do it together after having agreed on it Britain has to pursue policies in concert with other EU members. It appeared that both the accused were acting in concert in the attack upon the deceased. b) APplaying or singing at a concert They’re appearing in concert tonight at the Royal Concert Hall. → concert
Examples from the Corpusacting in concert• In so doing he seems to have been acting in concert with a Roman official called Seronatus.• The Regulation also applies to the acquisition of joint control by a number of companies acting in concert.• The calcium waves spreading through glial cells may constitute a long-range signalling network acting in concert with conventional neuronal networks.• The concert party provisions apply equally to the directors of the target and persons acting in concert with them.