nightmarenoun/ˈnaɪt.mɛə/

• 1

  A very unpleasant or frightening dream.

  • I had a nightmare that I tried to run but could neither move nor breathe.
  • July 18 2012, Scott Tobias, AV Club The Dark Knight Riseshttp://www.avclub.com/articles/the-dark-knight-rises-review-batman,82624/ With his crude potato-sack mask and fear-inducing toxins, The Scarecrow, a “psychopharmacologist” at an insane asylum, acts as a conjurer of nightmares, capable of turning his patients’ most terrifying anxieties against them.
• 2

  Any bad, miserable, difficult or terrifying situation or experience that arouses anxiety, terror, agony or great displeasure.

  • Cleaning up after identity theft can be a nightmare of phone calls and letters.
  • If Euston is not typically English, St. Pancras is. Its façade is a nightmare of improbable Gothic. It is fairly plastered with the aesthetic ideals of 1868, and the only beautiful thing about it is Barlow's roof. It is haunted by the stuffier kind of ghost. Yet there is something about the ordered whole of St. Pancras that would make demolition a terrible pity.
• 3

  archaicA demon or monster, thought to plague people while they slept and cause a feeling of suffocation and terror during sleep.

  • It haunted me, however, more than once, like a night-mare.
  • They plague and annoy lazy men-servants and untidy maids with frightful dreams; oppress them as the nightmare; bite them as fleas; and scratch and tear them like cats and dogs; and often in the night frighten, in the shape of owls, thieves and lovers, or, like Will-o-the-wisps, lead them astray into bogs and marshes, and perhaps up to those who are in pursuit of them.
• 4

  historicalA feeling of extreme anxiety or suffocation experienced during sleep; sleep paralysis.

  • The Night-mare generally ſeizes people ſleeping on their backs, and often begins with frightful dreams, which are ſoon ſucceeded by a difficult reſpiration, a violent oppreſſion on the breaſt, and a total privation of voluntary motion.
  • Had been afflicted in the night with that strange complaint called the nightmare.

nightmareverb/ˈnaɪt.mɛə/

• 1

  To experience a nightmare.

  • Brother Fary of Omaha was nightmaring the rest of the night.
  • It’s been 21,900 hours, 912 days, 130 Saturday nights, 30 months, 3 years since October 16, 1988 when I was stunned awake, straddled by a man I did not know. First I think I’m nightmaring.
• 2

  To imagine (someone or something) as in a nightmare.

  • She was the last person I’d expected to see, although I had not expected to see anyone at all. For a moment I thought it was a nightmare, and that I was nightmaring the whole thing.
  • Stars have no need of intimidation, which makes them mightier than all the godheads nightmared by mere humanity.
• 3

  To trouble (someone or something), as by a nightmare.

  • THe day is broke! Melpomene, be gone; / Hag of my Fancy, let me now alone: / Night-mare my ſoul no more; Go take thy flight / Where Traytors Ghoſts keep an eternal night; […]
  • Thou things imponderable dost price and weigh / By scales untrue ’gainst the gewgaws and gauds / O’ the World; thy ledger ’neath thy head dost lay / For pillow, nightmared with dreams of thy hoards.