bourdon

[boo r-dn, bawr-, bohr-] /ˈbʊər dn, ˈbɔr-, ˈboʊr-/
noun, Music.
1.
  1. the drone pipe of a bagpipe.
  2. the drone string of a stringed instrument.
2.
a low-pitched tone; bass.
3.
a pipe organ stop of very low pitch.
4.
the bell in a carillon having the lowest pitch.
Origin
1350-1400; Middle English < Middle French; see burden2
British Dictionary definitions for bourdon

bourdon

/ˈbʊədən; ˈbɔːdən/
noun
1.
a 16-foot organ stop of the stopped diapason type
2.
the drone of a bagpipe
3.
a drone or pedal point in the bass of a harmonized melody
Word Origin
C14: from Old French: drone (of a musical instrument), of imitative origin