An accordion is a hand-held musical instrument that has a keyboard or buttons and a bellows that blows air in and out. A street musician might play folk tunes on her accordion and collect donations in a hat.
One of the distinct features of an accordion is its bellows, which looks like a series of pleats at the center of the instrument, and which allows the player to push and pull the accordion as she plays, blowing air across reeds inside it. The accordion was invented in the early 1800s, and it's played in many countries around the world. The word comes from the German Akkordion, from Akkord, "musical chord" or "be in tune."