A nightmarish experience is one that is very unpleasant. It can be a scary experience, or it can be a confusing or frustrating one.
The nightmare was so terrifying that she couldn't stop thinking about it, even during the day.
The nightmare was so frightening that she couldn't fall asleep for hours after it was over.
adjective
extremely alarming
Synonyms:
1
His periodic moments of clarity startle and wrack him as fiercely as his nightmarish visions.
2
There is nothing nightmarish about it.
3
Dear God, that's a nightmarish situation.
4
They share a nightmarish effect on their victims.
5
In it, they are pursued by nightmarish creatures bent on their death.
6
Bacon's portraits are notable for their nightmarish quality.
7
Three talk pages it too nightmarish.
8
They are being subjected to mutilation of a nightmarish proportion.
9
They said that it was so difficult as to be almost nightmarish.