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.
2.
an extremely confused, entangled, or disordered place, situation, etc.: We just moved in, and the place is a mare's-nest.
a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.
an extraordinary or unusual thing, person, or event; an exceptional example or instance.
a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes.