n .
combined action ; agreement 연합을 이룬 행위 ; 협약

• By acting in concert, the three boys were able to tip over the car that none of them had been able to tip over while acting alone.
  세 소년이 힘을 합침으로써, 혼자서는 아무도 뒤집을 수 없었던 차를 뒤집을 수 있게 되었다.
• concerted effort 협력