The Collaborative International Dictionary
Euphonon
Euphonon \Eu"pho*non\, n. [See Euphony.] (Mus.) An instrument resembling the organ in tone and the upright piano in form. It is characterized by great strength and sweetness of tone.
Wiktionary
euphonon
n. (context music English) A musical instrument resembling the organ in tone and the upright piano in form.