koppelflöte

\\ˈkäpəlˌflād.ə, -flə̄d.ə, G ˈkȯpəlˌflœ̅tə\ noun (-s)

Etymology: German, from koppel tie, connection (from Middle High German koppel, kuppel, from Old French cople, couple pair, bond) + flöte flute, from Middle High German vloite, from Old French flaute, fleute — more at couple, flute

: an open flute stop in a pipe organ having a neutral tone and serving as a basis upon which to erect tonal pyramids of mutation ranks