This is the 1447th most frequent Swedish word.
förgäves
In vain.
In this sentence, "förgäves" expresses the idea that the effort made to locate the keys was unsuccessful and futile.
Han försökte förgäves att hitta sina nycklar.
He tried in vain to find his keys.
Here, "förgäves" highlights that despite working all night, their efforts were ultimately fruitless.
De arbetade förgäves hela natten för att rädda projektet.
They worked in vain all night to save the project.
In this context, "förgäves" denotes her repeated but unsuccessful attempts to persuade him.