ileum

noun

il·​e·​um ˈi-lē-əm How to pronounce ileum (audio)
plural ilea ˈi-lē-ə How to pronounce ileum (audio)
: the last division of the small intestine extending between the jejunum and large intestine
ileal
ˈi-lē-əl How to pronounce ileum (audio)
adjective

Examples of ileum in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The stool passes through the ileum into an ostomy pouch that attaches to the stoma outside your body. — Lindsay Curtis, Health, 31 Dec. 2024 Most absorption of vitamin B12 occurs in the ileum, the last and longest section of your small intestine. — Anna Giorgi, Verywell Health, 6 Nov. 2024

Word History

Etymology

New Latin, alteration of Latin ilia, plural, groin, viscera

First Known Use

1682, in the meaning defined above

Time Traveler
The first known use of ileum was in 1682

Rhymes for ileum

See All Rhymes for ileum

Browse Nearby Words

ilesite
ileum
ileus
See all Nearby Words

Cite this Entry

“Ileum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ileum. Accessed 4 Apr. 2025.

Copy Citation

Share

Kids Definition

ileum

noun
il·​e·​um ˈil-ē-əm How to pronounce ileum (audio)
plural ilea -ē-ə How to pronounce ileum (audio)
: the last part of the small intestine between the jejunum and the large intestine
ileal
-ē-əl How to pronounce ileum (audio)
adjective

Medical Definition

ileum

noun
il·​e·​um ˈil-ē-əm How to pronounce ileum (audio)
plural ilea -ē-ə How to pronounce ileum (audio)
: the last division of the small intestine that constitutes the part between the jejunum and large intestine and in humans forms the last three fifths of the part of the small intestine beyond the end of the duodenum and that is smaller and thinner-walled than the jejunum with fewer circular folds but more numerous Peyer's patches

More from Merriam-Webster on ileum

Britannica.com: Encyclopedia article about ileum

Love words? Need even more definitions?

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

Popular in Grammar & Usage

See More

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)

The Difference Between 'i.e.' and 'e.g.'

Why is '-ed' sometimes pronounced at the end of a word?

Words You Always Have to Look Up

Democracy or Republic: What's the difference?
See More

Popular in Wordplay

See More

What do SCOTUS, POTUS, and FLOTUS mean?

Top 10 Sophisticated Insults

More Words with Remarkable Origins

Terroir, Oenophile, & Magnum: Ten Words About Wine

8 Words for Lesser-Known Musical Instruments
See More

Popular

See More

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)

What do SCOTUS, POTUS, and FLOTUS mean?

Top 10 Sophisticated Insults
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
burrowing owl athene cunicularia tilts its head outside its burrow on marco island florida
Guess the Curious Origins of These Everyday Words Oh, that’s where that comes from…
See All