SINCE 1828

An Encyclopædia Britannica Company

Medical Dictionary

sleep paralysis

noun

medical Definition of sleep paralysis

:a complete temporary paralysis occurring in connection with sleep and especially upon waking

Seen and Heard

What made you want to look up sleep paralysis? Please tell us where you read or heard it (including the quote, if possible).

show

WORD OF THE DAY

hew

play

to conform or adhere

Words at Play

alt-59e77dc36c593

The Origins of 'Lobbyist'

From the front hallways to the back rooms

alt-59e673567065d

The History of the Word 'Terrorism'

Noah Webster first entered the term in 1840

alt-59e65152518a6

'Regimen' vs. 'Regiment'

The rule of thumb for words about rules

alt-59e50f5a357b4

'Spox' May Go On The Record

From newsroom lingo to the mainstream

Ask the Editors

video-title-words-of-the-year-1066

Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless

Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals

Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

one-green-toy-robot-amidst-many-red-toy-robots

The Exceptions Quiz III

Which of these things doesn't belong?

Take the quiz

knupfer-painting-solon-before-croesus

Forms of Government Quiz

Name that government! Or something like that.

Take the quiz

Spell It

Can you spell these 10 commonly misspelled words?

Take the quiz

Syn City

Build a city of skyscrapers—one synonym at a time.

Play the game