Illustration of helicon
helicon
noun
hel·i·con ˈhe-lə-ˌkän 
-li-kən
: a large circular tuba similar to a sousaphone but lacking an adjustable bell
Example Sentences
Recent Examples on the Web Allan Jaffe, who played the helicon, a brass instrument, was the link to the musicians and sent them out on the road as the Preservation Hall Jazz Band. 
New York Times, 31 Dec. 2021
New York Times, 31 Dec. 2021 Word History
Etymology
probably from Greek helik-, helix + English -on (as in bombardon); from its tube's forming a spiral encircling the player's body
First Known Use
circa 1875, in the meaning defined above
Geographical Definition
Helicon
geographical name
Hel·i·con ˈhe-lə-ˌkän
-li-kən
variants or Modern Greek Elikón
ˌe-lē-ˈkȯn
mountain 5735 feet (1748 meters) high in southwestern Boeotia, east central Greece, near the Gulf of Corinth