hard nut to crack

Noun

 * 1)  A problem that is challenging to solve.
 * 2)  A situation, person, group, etc. which is difficult to overcome or deal with.
 * 3)  A place, opportunity, etc. to which it is difficult to gain entry.
 * 4)  An amount that is difficult to finance.
 * 1)  A situation, person, group, etc. which is difficult to overcome or deal with.
 * 2)  A place, opportunity, etc. to which it is difficult to gain entry.
 * 3)  An amount that is difficult to finance.
 * 1)  A place, opportunity, etc. to which it is difficult to gain entry.
 * 2)  An amount that is difficult to finance.
 * 1)  An amount that is difficult to finance.
 * 1)  An amount that is difficult to finance.
 * 1)  An amount that is difficult to finance.

Usage notes

 * Tough/er/est nut to crack is by far the most common form in COCA (US), about equal to hard/er/est nut to crack at BNC (UK).

Translations

 * Chinese:
 * Mandarin: 难以攻克的困难
 * Danish:
 * Finnish: kova pähkinä purtavaksi
 * German: harte Nuss
 * Hebrew:
 * Hungarian: kemény dió
 * Polish:
 * Russian:
 * Spanish: hueso duro de roer
 * Turkish: çetin çeviz