1 : an evil spirit formerly thought to oppress people during sleep
2 : a frightening dream that usually awakens the sleeper
3 : something (as an experience, situation, or object) having the monstrous character of a nightmare or producing a feeling of anxiety or terror
Since starting the new medication, John routinely experiences vivid dreams when he sleeps and even suffers from frequent nightmares.
"When the Detroit Tigers opened Comerica Park for the 2000 season, the stadium immediately developed a reputation as a right-handed hitter's nightmare, and the expansive playing surface helped earn it the nickname Comerica State Park." -- From an article by Andrew Keh in The New York Times, November 2, 2011
Did You Know?
Looking at "nightmare," you might guess that it is a compound formed from "night" and "mare." If so, your guess is correct. But while the "night" in "nightmare" makes sense, the "mare" part is less obvious. Most English speakers know "mare" as a word for a female horse or similar equine animal, but the "mare" of "nightmare" is a different word, an obsolete one referring to an evil spirit that was once thought to produce feelings of suffocation in people while they slept. By the 14th century the mare was also known as a "nightmare," and by the late 16th century "nightmare" was also being applied to the feelings of distress caused by the spirit, and then to frightening or unpleasant dreams.
Test Your Vocabulary
What noun begins with "b" and refers to a female spirit in Gaelic folklore whose appearance or wailing warns a family that one of them will soon die? The answer is ...