melodeon

noun

Plural: melodeons

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.

Examples:

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.)