1. noun; A gurgling or bubbling sound, especially the sound of running water.
  2. verb; To bubble and gurgle. To make the sound of bubbling and gurgling.
  3. noun; A rapid, excited flow of speech. Synonym with 'babble'.
  4. verb; To speak quickly in an excited manner.
  5. noun; Turbulence in a flow (liquid or gas) against a streamlined body (techspeak; a separation in the boundary layer). Also, turbulence in an airplane resulting from this. Synonym with 'nibble'. 'Burble point' refers to the point in the increase of angle of attack in which turbulence first becomes evident.
  6. noun; In skydiving, the turbulent air just behind the diver's back (assuming that the diver is facing downwards). Synonym with 'wake'. Burbles can prevent parachutes from deploying if the diver does not know how to deal with them.
  7. verb, Scottish; Confuse, muddle.

Etymology: burble comes from the Middle English burblen, to bubble.


Sources:
Dictionary.com
Webster's Third New International Dictionary
http://www.makeithappen.com/spsj/burble.htm
http://www.petester.com/html/bachap02.html