a musical instrument with a folding middle part that is played by pushing both ends together with the hands and pressing buttons

to fold, crush, or push together

In the accident, several cars concertinaed into each other. 事故中，几辆车撞成一团。

figurative Could we concertina the three meetings into one morning? 我们能把3个会议压缩在一个上午开吗？