1. A musical instrument with a fan-folded zigzagged air bag characteristic of the accordion family.
2. Figuratively, any object or shape resembling the unique appearance of accordions (for example, z-foldable doors, buses or trains with ruffled interconnecting segments, air-blowing devices, etc⋅). Specifically: An articulated bus comprising two or more rigid sections linked by a pivoting joint (articulation) enclosed by protective bellows inside and outside and a cover plate on the floor; banana bus; bendy bus; tandem bus; vestibule bus; wiggle wagon; stretch bus; accordion bus.
Finally, the melodeon's driver was forced to back out of the street. He had to drive reversewise all the way to the nearest intersection to alleviate the imminent traffic jam: The schoolward turn was already usurped by the first bus, while the road in front of and behind him became occluded by cars that made passage impossibly narrow. (Source: J∙ Okram - The Mystery of the Rammed Key.)