An illusion.
An optical phenomenon in which light is refracted through a layer of hot air close to the ground, often giving the illusion of a body of water.
To cause to appear as or like a mirage.
A very bad or frightening dream.
Any bad, miserable, difficult or terrifying situation or experience that arouses anxiety, terror, agony or great displeasure.
A feeling of extreme anxiety or suffocation experienced during sleep; Sleep paralysis.
To have a nightmare.