stoma

American  

[stoh-muh] / ˈstoʊ mə /

noun

• stomata,
  plural
• stomas
  plural

1. Botany. Also any of various small apertures, especially one of the minute orifices or slits in the epidermis of leaves, stems, etc., through which gases are exchanged.

2. Zoology. a mouth or ingestive opening, especially when in the form of a small or simple aperture.

3. Medicine/Medical. an artificial opening between two hollow organs or between one hollow organ and the outside of the body, constructed to permit the passage of body fluids or waste products.

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stoma British  

/ ˈstəʊmə /

noun

1. botany an epidermal pore, present in large numbers in plant leaves, that controls the passage of gases into and out of a plant

2. zoology anatomy a mouth or mouthlike part

3. surgery an artificial opening made in a tubular organ, esp the colon or ileum See colostomy ileostomy

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stoma Scientific  

/ stō′mə /

• stomata
  plural

1. Botany One of the tiny openings in the epidermis of a plant, through which gases and water vapor pass. Stomata permit the absorption of carbon dioxide necessary for photosynthesis from the air, as well as the removal of excess oxygen. Stomata occur on all living plant parts that have contact with the air; they are especially abundant on leaves. A single leaf may have many thousands of stomata. Each stoma is generally between 10 to 30 microns in length and is surrounded by a pair of crescent-shaped cells, called guard cells. The guard cells can change shape and close the stoma in order to prevent the loss of water vapor.

2. Botany See Note at transpiration

3. Zoology A mouthlike opening, such as the oral cavity of a nematode.

4. Medicine A temporary or permanent opening in a body surface, especially the abdomen or throat, that is created by a surgical procedure, such as a colostomy or tracheostomy.

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Other Word Forms

Derived Forms

• stomal
  adjective

Inflected Forms

Nouns

• stomas
  plural
• stomata
  plural

Etymology

Origin of stoma

First recorded in 1675–85; from New Latin, from Greek stóma “mouth”

Explanation

In humans, a stoma is any opening or hole in the body. In plants, it's an opening that acts as a sort of mouth, allowing gas exchange. Stoma is a Greek word that means "mouth," and your mouth is indeed one kind of stoma, or natural opening in your body. Ears and nostrils are also stomas, as are holes created through surgery. An operation to help a patient breathe might create a stoma in their neck, for example. You can only see tiny plant stomas through a microscope; these small openings allow plants to take in the carbon dioxide they need for photosynthesis.

Example Sentences

See Examples For:

stoma stomas stomata

"I have swallowed more dust than bread," he said in his living room, as he showed the stoma bag he now has to use.

From Barron's ● Aug. 28, 2026

Natalie has since had further surgery, including reversal of the stoma and treatment for complications including a hernia and ongoing wound problems.

From BBC ● Aug. 26, 2026

She said: "Seeing stoma bags that are glittery and frilly it shows people that we're not just patients we're actually people."

From BBC ● Mar. 24, 2026

Her illness had led to her pulling off her stoma bag that collects bodily waste from the abdomen.

From BBC ● Sep. 22, 2025

The layer forming the roof is called the "epidermis," and the small opening left leading into the chamber is bounded by a special ring of cells and forms the "stoma" or air-pore.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" by Various

She also has two stomas in place for life because much of her bladder and bowel have had to be removed.

From BBC ● Nov. 17, 2024

"The bear makes opening conversations about stomas a lot easier because the child can explain what's happened to them using their bear," said Ms Gow.

From BBC ● Oct. 25, 2024

She says the reaction from her sto-mates, people who also have stomas, to her being on the show and modelling has been "amazing".

From BBC ● Jan. 30, 2024

Gill Castle swam mostly in the dark from Dover to France in 14 hours to raise awareness of birth injures and people with stomas.

From BBC ● Sep. 12, 2023

She has undergone 16 separate surgeries and has two stomas and catheter.

From BBC ● Jun. 25, 2023

This limitation matters because stomata respond quickly to changes in light, temperature, humidity and carbon dioxide levels.

From Science Daily ● Jan. 7, 2026

As carbon dioxide levels in the atmosphere increase, plants may need to open their stomata less frequently, leading to decreased transpiration and preserving more groundwater.

From Los Angeles Times ● Dec. 20, 2024

Unlike flowering plants, mosses do not use stomata for CO2 entry and therefore may have less access to the available CO2.

From Science Daily ● Nov. 14, 2023

But when the air and soil are so dry that they can’t meet demand, a tree will eventually close the stomata, or pores, on its leaves to avoid losing precious water.

From Los Angeles Times ● Aug. 26, 2023

The prevailing views at the present time are in favor of the artificial nature of the stomata and pores in the walls of the blood-vessels.

From A System of Practical Medicine by American Authors, Vol. I Volume 1: Pathology and General Diseases by Various