A person or thing that irritates or instigates.
Synonym of gadabout (“a person who restlessly moves from place to place, seeking amusement or the companionship of others”)
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.
A person who takes without giving back; a bloodsucker.
A person who upsets the status quo by posing novel or upsetting questions, or attempts to stimulate innovation by being an irritant.
One with an obsessive interest in something, particularly (originally derogatory) obsessive Japanese fans of anime or manga.