Any bad, miserable, difficult or terrifying situation or experience that arouses anxiety, terror, agony or great displeasure.
A very bad or frightening dream.
A feeling of extreme anxiety or suffocation experienced during sleep; Sleep paralysis.
To have a nightmare.
Intense dread, fright, or fear.
The action or quality of causing dread; terribleness, especially such qualities in narrative fiction.
A night terror.
Terrorism.
Something or someone that causes such fear.