to faint; to pass out
Hacía tanto calor que pensé que me iba a desmayar.
It was so hot I thought I was going to faint.
Rosie, ven, creo que se va a desmayar.
Rosie, come here, I think she's going to faint.
— Las noches de Cabiria (1957)
Me voy a desmayar.
I'm going to faint.
— La diva (1981)
Me siento mareado, me voy a desmayar.
I feel dizzy; I'm going to faint.
— Los hombres detrás del sol 2: El laboratorio del diablo (1992)
Tom sintió de repente como si se fuera a desmayar.
Tom suddenly felt as if he were going to faint.
Creo que me voy a desmayar.
I think I'm going to faint.
Se veía como si ella se fuera a desmayar.
She looked like she was about to faint.