An unforeseen event causing great loss, upset or unpleasantness of whatever kind.
An unexpected natural or man-made catastrophe of substantial extent causing significant physical damage or destruction, loss of life or sometimes permanent change to the natural environment.
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.