What is the meaning of Gadfly?

Any dipterous (“two-winged”) insect or fly of the family Oestridae (commonly known as a botfly) or Tabanidae (horsefly), noted for irritating animals by buzzing about them, and biting them to suck their blood; a gadbee.

1. A person or thing that irritates or instigates.
   1. A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.

      A person or thing that irritates or instigates.

      1. A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.

         A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.

         Synonym of gadabout (“a person who restlessly moves from place to place, seeking amusement or the companionship of others”).

         A person who takes without giving back; a bloodsucker.

         Source: wiktionary.org