a thorn in side

Also found in: Dictionary, Thesaurus, Medical, Encyclopedia.

a thorn in somebody's/something's side

also a thorn in the side of somebody/something
someone or something that continually causes problems Most teachers usually have one student in their class who is a thorn in their side. The town finds the casino a thorn in its side, even though it brings huge numbers of tourists to the town. Health inspectors are a thorn in the side of most restaurant owners.
See also: side, thorn