Instrument with O

• Organ

  A classic keyboard musical instrument. Fits O!

• Ocarina

  Wind instrument; real and well-known. Good O!

• Oud

  Real string instrument from the Middle East.

• Organistrum

  Medieval string instrument; totally valid!

• Odometer

  Measuring instrument for distance; yes!

• Organs

  Plural of organ, a real musical instrument.

• old guitar

  An instrument; 'old' is fine for O here.

• Oscilloscope

  Scientific instrument for signals; yes!

The words in the list Instrument with O come from players of the word game Categories game.