accordion vs piano accordion

accordion

noun
  • A box-shaped musical instrument with means of keys and buttons, whose tones are generated by play of the wind from a squeezed bellows upon free metallic reeds. 

  • A set of items (concepts, links, or otherwise) that can be packed and unpacked cognitively, or their representation as a set of virtual objects. 

  • A vertical list of items that can be individually expanded and collapsed to reveal their contents. 

verb
  • To fold up, in the manner of an accordion 

piano accordion

noun
  • an accordion with a keyboard similar to that of a piano 

How often have the words accordion and piano accordion occurred in a corpus of books? (source: Google Ngram Viewer )