to faint, to pass out
Se ela desmaiar de novo eu te demito.
If she faints again, I'll fire you.
— O Salário do Medo (1953)
Eu acho que Tom vai desmaiar.
I think Tom is going to faint.
Estava tão quente no estádio que eu pensei que fosse desmaiar.
It was so hot in the stadium that I thought I was going to faint.