a curved flat piece of wood that you throw and
that can fly in a circle and come back to you.
Boomerangs were first used by Australian Aborigines
as weapons when they were hunting: (figurative)
The plan had a boomerang effect (= caused unexpected
harm to the person responsible for it).
[v] if a plan boomerangs on sb, it hurts them instead
of the person it was intended to hurt.
& Rural News