Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

nictitating membrane

noun

Definition of nictitating membrane

  1. :  a thin membrane found in many vertebrates at the inner angle or beneath the lower lid of the eye and capable of extending across the eyeball

See nictitating membrane defined for kids

From the M-W Editors

time-traveler-quiz-which-word-came-first
Time Traveler Quiz: Which Word Came First?
alt-5991e113c97b3
Trending: Trump Calls Racism 'Repugnant'
alt-599492594f435
How 'Wonderful' Lost Its Sense of Wonder
image1458426927
Good Words for Strong Flavors

First Known Use of nictitating membrane

1713

Medical Dictionary

nictitating membrane

noun

Medical Definition of nictitating membrane

  1. :  a thin membrane found in many vertebrate animals at the inner angle or beneath the lower lid of the eye and capable of extending across the eyeball—called also membrana nictitans, third eyelid

Seen and Heard

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

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

perfunctory

play

done merely as a duty

Get Word of the Day daily email!

TRENDING NOW

  1. repugnant Trump clarifies his position on racism

  2. white nationalist, white supremacist Trending in 2017

  3. bereft "Lacking something needed, wanted, or expected"

  4. impanel "To choose people to serve on a jury"

  5. cosmopolitan "Worldly"

SEE ALL

BROWSE DICTIONARY

nictitating membrane

Test Your Vocabulary

Time Traveler Quiz: Which Word Came First?

  • time-traveler-quiz-which-word-came-first
  • Which came first?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-599492594f435
How 'Wonderful' Lost Its Sense of Wonder

A case of semantic bleaching

dog-covering-face
Don't Let Reading This Be Another 'Coulda' 'Shoulda' 'Woulda'

PSA: They're three separate words.

image1458426927
Food Words for Strong Flavors

A tasting menu of vivid flavor descriptions

alt-5993066a3afad
What's the Plural of 'Maitre d''?

Use this word to confuse a French speaker.

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'

payday
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

time-traveler-quiz-which-word-came-first
Time Traveler Quiz: Which Word Came First?

Which word entered the English language first?

Take the quiz
name-more-food
Name More Food!

Test your knowledge of food vocabulary!

Take the quiz
Name That Thing
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz
SCRABBLE® Sprint
SCRABBLE® Sprint

SCRABBLE® fans, sharpen your skills!

Play the game