stubbornknot
nounUK /ˈstʌbən nɒt/
US /ˈstʌbərn nɑːt/
A knot that is very hard to untie.
My shoelace had a stubbornknot that took ten minutes to undo.
OTHER MEANINGS
2. A problem that is very hard to solve.
The broken pipe was a stubbornknot for the plumber.
3. A person who refuses to change their mind.
Her little brother is a stubbornknot about bedtime.
4. A tricky part in a story or puzzle.
The last clue was a stubbornknot for the whole team.