to trust, to rely on
No hay que fiarse de las apariencias.
You can't judge by appearances.
A Tom no le gusta fiarse de otros.
Tom doesn't like relying on others.
Hablando francamente, él no es de fiarse.
Frankly speaking, he's not to be trusted.
Mira que fiarse de su mujer un tipo listo como tú.
A smart guy like you, actually trusting his wife.
— Carandiru (2003)
No es cuestión de fiarse, guardia.
It's not a matter of trusting anyone, guard.
— Ladrón de bicicletas (1948)