This is the 6372nd most frequent Catalan word.
nus
Knot.
In this sentence, 'nus' is used in its literal meaning as a physical knot.
El nus de la corda estava difícil de desfer.
The knot of the rope was difficult to untie.
Here, 'nus' is used metaphorically to describe an emotional tension or discomfort.
El nus a l'estómac no em deixava tranquil.
The knot in my stomach wouldn't let me be calm.
In this usage, 'nus' represents the central or key part of an issue, often metaphorically.