Concert overture

What is Concert overture?

Concert overture definition and meaning on Dictionary terms:
a musical instrument resembling an accordion but having buttonlike keys, hexagonal bellows and ends, and a more limited range.
concertina wire.

verb (used without object), conA.cerA.tiA.naed [kon-ser-tee-nuha??d] /E?kE?na??sE?rE?tia??nE?d/, [kon-ser-tee-nuh-ing] /E?kE?na??sE?rE?tia??nE?a??EaA?/.
to fold, crush together, or collapse in the manner of a concertina: The car concertinaed when it hit the truck.

verb (used with object), conA.cerA.tiA.naed [kon-ser-tee-nuha??d] /E?kE?na??sE?rE?tia??nE?d/, [kon-ser-tee-nuh-ing] /E?kE?na??sE?rE?tia??nE?a??EaA?/.
to cause to fold or collapse in the manner of a concertina.

of, relating to, or resembling a concertina: concertina pleats.