concertina

A concertina can be a musical instrument: a small, button-operated bellows instrument related to the accordion, often heard in folk music. But the word is also used for anything that is folded into many neat pleats so it can open out and close up again. Think of the way a paper map folds into a compact packet, or how the flexible middle section of a "bendy bus" works—those are examples of a concertina-style fold.

You might say a brochure was folded concertina-style, or that a ladder, partition, or staircase opens like a concertina to save space. And in security settings, "concertina wire" means a large coil of barbed or razor wire that can be pulled open quickly into a barrier.

The word "concertina" carries two primary meanings. Firstly, it refers to a specific musical instrument—a free-reed bellows instrument with buttons on both ends. Unlike the standard piano accordion, a concertina is typically hexagonal (sometimes octagonal) and is celebrated for its bright, rhythmic tone, often associated with sea shanties and traditional Irish or English folk music. The player creates sound by pushing and pulling the bellows while pressing buttons that open valves, letting air flow past the reeds.

However, "concertina" also describes a method of folding something into narrow, parallel pleats that can be drawn out or compressed. This "concertina-folding" is a staple of efficient design, used for everything from road maps and fire hoses to the pleated fabric of certain blinds and curtains. In security and military contexts, the word is also used to describe "concertina wire"—large coils of barbed or razor wire that can be expanded quickly to form a formidable barrier.

The term originated in the 19th century, coined by the inventor Sir Charles Wheatstone. He likely chose the name to suggest a portable instrument made for concert playing. Today, whether you are listening to someone play a jig or describing the way a brochure is neatly tucked away, the word evokes a sense of steady expansion and contraction. You might say, "The emergency ladder was stored in a concertina fold," or "He skillfully played a traditional melody on the concertina."