epithelium

American  

[ep-uh-thee-lee-uhm] / ˌɛp əˈθi li əm /

noun

Biology.

• epitheliums,
  plural
• epithelia
  plural

1. any plant or animal tissue that covers a surface or lines a cavity, and that also performs any of various secretory, transporting, or regulatory functions.

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epithelium British  

/ ˌɛpɪˈθiːlɪəm /

noun

1. an animal tissue consisting of one or more layers of closely packed cells covering the external and internal surfaces of the body. The cells vary in structure according to their function, which may be protective, secretory, or absorptive

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epithelium Scientific  

/ ĕp′ə-thē′lē-əm /

• epithelia
  plural

1. The thin, membranous tissue that lines most of the internal and external surfaces of an animal's body. Epithelium is composed of one or more layers of densely packed cells. In vertebrates, it lines the outer layer of the skin (epidermis), the surface of most body cavities, and the lumen of fluid-filled organs, such as the gut or intestine.

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Other Word Forms

Derived Forms

• epithelial
  adjective

Inflected Forms

Nouns

• epithelia
  plural
• epitheliums
  plural

Etymology

Origin of epithelium

First recorded in 1740–50; from New Latin, from Greek epi- epi- ( def. ) + thēl(ḗ) “teat” + New Latin -ium -ium ( def. )

Compare meaning

How does epithelium compare to similar and commonly confused words? Explore the most common comparisons:

• endothelium vs. epithelium

Example Sentences

See Examples For:

epithelium epithelia epitheliums

In healthy conditions, the intestinal epithelium renews itself every three to five days.

From Science Daily ● Jan. 3, 2026

"Barrett's esophagus is characterized by the replacement of the resident squamous epithelium of the esophagus by other cell types that are not normally found in this tissue," says the scientist.

From Science Daily ● Apr. 11, 2024

The inhaled air is trapped on the olfactory epithelium and/or the Jacobson’s organ, giving kitties an extra chance to detect scent molecules.

From National Geographic ● Jan. 2, 2024

Many tiny hair-like cilia protrude from the olfactory receptor cell’s dendrite and into the mucus covering the surface of the olfactory epithelium.

From Textbooks ● Jan. 1, 2015

Electrodes in the olfactory bulbs of salmon will fire when the olfactory epithelium is exposed to water from their spawning grounds, whereas water from other streams causes no response.

From "The Lives of a Cell" by Lewis Thomas

"The squamous epithelia of the esophagus and the columnar epithelia of the stomach meet at the gastroesophageal junction," explains Dr. Naveen Kumar Nirchal, one of the first authors of the study.

From Science Daily ● Apr. 11, 2024

"Our results therefore suggest that, while protecting epithelia, mucus constitutes a breeding ground for biofilms," they explain.

From Salon ● Aug. 5, 2023

"Our results therefore suggest that, while protecting epithelia, mucus constitutes a breeding ground for biofilms."

From Salon ● Aug. 5, 2023

Bloodhounds were bred to have a better sense of smell, and thus have more olfactory receptors and larger olfactory epithelia.

From Textbooks ● Jun. 9, 2022

There may even be odorants that fire off receptors in our olfactory epithelia without our being conscious of smell, including signals exchanged involuntarily between human beings.

From "The Lives of a Cell" by Lewis Thomas

Inwardly he was lined with cast-off epitheliums, as outwardly he was clad in the painter's discarded coats.

From The Troll Garden and Selected Stories by Willa Sibert Cather