A gadfly is an irritating person, a nuisance who will often ask too many questions or lob lots of criticisms in order to get his or her way.

Gadfly can also refer to an actual fly. The next time you see a cow swatting at the air with her tail, look closer because she might actually be shooing away an annoying gadfly. This is any kind of fly that likes to pester, and even bite, livestock. The prefix gad is an old word for “spike” or “pointed stick” which can be thought of, in this case, as similar to a stinger. So if your office mate is continuously buzzing around your desk with stinging comments, call him a gadfly and try to shoo him back to his own desk.

Primary Meanings of gadfly

any of various large flies that annoy livestock
a persistently annoying person
Full Definitions of gadfly

n any of various large flies that annoy livestock

show 6 types...
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stout-bodied hairy dipterous fly whose larvae are parasites on humans and other mammals
warble fly
hairy bee-like fly whose larvae produce lumpy abscesses (warbles) under the skin of cattle
cleg, clegg, horse fly, horsefly
large swift fly the female of which sucks blood of various animals
Gasterophilus intestinalis, horse botfly
parasitic chiefly on horses
Dermatobia hominis, human botfly
large tropical American fly; parasitic on humans and other mammals
Oestrus ovis, sheep botfly, sheep gadfly
larvae are parasitic on sheep
Type of:
two-winged insects characterized by active flight

n a persistently annoying person

blighter, cuss, pest, pesterer
nudnick, nudnik
(Yiddish) someone who is a boring pest
Type of:
persecutor, tormenter, tormentor
someone who torments

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