the only thing
Lo único cierto era que pagaba bien a su gente.
The only certainty was that he paid his people well.
— Nosferatu (1922)
Lo único seguro es que tengo que intentarlo.
The only thing that's certain is that I have to try.
Lo único malo era eso, que era una puta.
The only bad thing was that she was a whore.
— Old Boy (2003)
Eso es lo único de lo que no tendrás que preocuparte.
That's the one thing you won't have to worry about.
— The Running Man (2025)
Cuando viene mi hija, es lo único constante que tiene.
When my daughter comes, it's the only constant she has.
— Song Sung Blue - Canción para dos (2025)
Lo único constante en este mundo es el cambio.
The only constant in this world is change.