Definition of euphonium
: a brass instrument smaller than but resembling a tuba and having a range from B flat below the bass staff upward for three octaves
Origin of euphonium
Greek euphōnos + English -ium (as in harmonium)
First Known Use: 1865
Seen and Heard
What made you want to look up euphonium? Please tell us where you read or heard it (including the quote, if possible).