bourdon

noun

1. The burden or bass of a melody.

2. The drone pipe of a bagpipe.

3. The lowest-pitched stop of an organ.

4. The lowest-pitched bell of a carillon.

5. A large, low-pitched bell not part of a diatonically tuned ring of bells.

6. A bumblebee, genus Bombus.

7. A pilgrim's staff.