gadfly

Definition of Gadfly in English :

a persistently annoying person

2. gadfly

any of various large flies that annoy livestock

WordNet Lexical Database for English. Princeton University. 2010.

Gadfly

noun plural -flies

1.

any of various large dipterous flies, esp the horsefly, that annoy livestock by sucking their blood

2.

a constantly irritating or harassing person

nounWord forms: plural ˈgadˌflies

1.

any of several large flies, as the horsefly, that bite livestock

2.

a person who annoys others, esp. by rousing them from complacency

n.

1. A persistent irritating critic; a nuisance.

2. One that acts as a provocative stimulus; a goad.

3. Any of various flies, especially a warble fly, botfly, or horsefly, that bite or annoy livestock and other animals.