mare's-nest

[ mairz-nest ]
/ ˈmɛərzˌnɛst /

noun

something imagined to be an extraordinary discovery but proving to be a delusion or a hoax: The announced cure for the disease was merely another mare's-nest.
an extremely confused, entangled, or disordered place, situation, etc.: We just moved in, and the place is a mare's-nest.

Origin of mare's-nest

First recorded in 1610–20

British Dictionary definitions for mare's-nest

mare's-nest

noun

a discovery imagined to be important but proving worthless
a disordered situation