unbreakableknot
nounUK /ʌnˈbreɪkəbəl nɒt/
US /ʌnˈbreɪkəbəl nɑːt/
A knot that is very hard to untie.
The sailor tied an unbreakableknot so the rope would not come loose.
OTHER MEANINGS
2. A problem that is very hard to solve.
Their argument became an unbreakableknot that no one could untangle.
3. A very strong bond between people.
The friendship between the two girls was an unbreakableknot.
4. A tricky puzzle or riddle.
The last question on the test was a real unbreakableknot.