Synonyms

hard nut to crack

Idioms

Also, tough nut to crack. A difficult problem; also, an individual who is difficult to deal with. For example, This assignment is a hard nut to crack, or It won't be easy getting her approval; she's a tough nut to crack. This metaphoric expression alludes to hard-shelled nuts like walnuts. [Early 1700s]

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023