crux
US /ˈkrʌks/
UK /ˈkrʌks/

1.
quid, punto crucial, meollo
the most important or essential point of an issue or problem
:
•
The crux of the matter is that we don't have enough funding.
El quid de la cuestión es que no tenemos suficiente financiación.
•
He finally got to the crux of his argument.
Finalmente llegó al punto crucial de su argumento.