This is the 10357th most frequent French word.
inutilement
Uselessly.
In this sentence, 'inutilement' is used to mean that the effort spent was unnecessary because the project wasn't utilized.
Il a travaillé inutilement sur ce projet, car personne ne l'a utilisé.
He worked pointlessly on this project, as no one used it.
Here, 'inutilement' signifies that the act of worrying was unneeded as the friends were perfectly fine.
Elle s'est inquiétée inutilement pour ses amis, qui allaient très bien.
She worried unnecessarily for her friends, who were doing very well.
In this example, 'inutilement' implies that the waiting turned out to be unnecessary due to the cancellation of the meeting.