piano accordion
From Longman Dictionary of Contemporary Englishpiano accordionpiˌano acˈcordion noun [countable] British English an accordionExamples from the Corpuspiano accordion• Normally a mouth organ or a piano accordion accompanies the music and plays the melody.• Noel Bridgeman's piano accordion takes over where Dooley Wilson's piano left off, and adds just the right ingredient.• I've been playing the piano and the piano accordion for about 60 years.