Definition of "gadfly" in English

noun

1. 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.

2. A person or thing that irritates or instigates.

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

4. A person who takes without giving back; a bloodsucker.

   • He’s a regular gadfly and takes advantage of his friend’s generosity.