# hard nut to crack

idiom

Source: https://englishreference.com/idiom/hard-nut-to-crack
Updated: 2026-08-10

## Meaning

A problem that is challenging to solve.

## Examples

- This math problem is a hard nut to crack.
- The company tried to improve sales, but the local market proved to be a hard nut to crack.
- Despite the team's extensive research and innovative strategies, the underlying cause of the system failure remained a hard nut to crack for the engineers.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.