bourdon

noun7

1. •
   The drone pipe of a bagpipe.
2. •
   The lowest-pitched stop of an organ.

   • The dim roar of London was like the bourdon note of a distant organ. — 1890
3. •
   The lowest-pitched bell of a carillon.
4. •
   A large, low-pitched bell not part of a diatonically tuned ring of bells.
5. •
   (historical) a pilgrim's staff.

   • The left hand was gone, this held the bourdon or pilgrim's staff, a small portion only of which appeared over the scrip. — 1883
6. •
   A bumblebee, genus Bombus.
7. •
   (no longer used) The burden or bass of a melody.

   • The earth tremors resumed and made a bourdon to the loud psalms that they sang, interspersed with the odd ode of Horace recited by Silas. — 1985

noun1

1. •
   A flute stop on an organ of 8', 16' or 32', generally characterized by a low, dark tone.