Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “nightmare”

nightmare

noun [C] uk   /ˈnaɪt.meər/ us    /-mer/
B1 a very upsetting or frightening dream: a terrifying nightmare I shouldn't have watched that movie - it'll give me nightmares.Dreaming B1 an extremely unpleasant event or experience or possible event or experience: The whole journey was a nightmare - we lost our luggage and we arrived two days late. Being trapped underwater is my worst nightmare.Difficult situations and unpleasant experiencesAccidents and disasters
nightmarish
adjective uk   /-meə.rɪʃ/ us    /-mer.ɪʃ/
Serious and unpleasantNot attractive to look atInformal words for bad
nightmarishly
adverb uk   /-meə.rɪʃ.li/ us    /-mer.ɪʃ.li/
Serious and unpleasantNot attractive to look atInformal words for bad
(Definition of nightmare from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of nightmare?
Browse related topics

You are looking at an entry to do with Difficult situations and unpleasant experiences, but you might be interested in these topics from the Easy and difficult topic area:

Add Cambridge dictionaries to your browser to your website

Definitions of “nightmare” in other dictionaries

Word of the Day

aptitude

a natural ability or skill

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More