hard nut to crack

1. 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]

Example Sentences

The $60 level proved a strong support and “is going to be a hard nut to crack now back to the upside,” he adds.

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“It’s a very hard nut to crack. The Russians could spend many months and much effort storming Lysychansk,” military analyst Oleh Zhdanov told the AP.

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“Bob is reclusive and quiet and a hard nut to crack,” Pullman said.

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Voice control is a hard nut to crack.

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“This place is a hard nut to crack,” Newgarden said.

Read more on Los Angeles Times