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 always say my stoma bag is just new accessory. It's just another bag and that was where the whole idea came from to like make covers for it and have it as an accessory."

From BBC ● Mar. 24, 2026

The brand works with people with disabilities to create adaptable jeans, stoma bags, and other pieces of clothing.

From BBC ● Mar. 24, 2026

"But then as soon as I had my stoma bag, I was like, 'Oh, right well, let's make this work again.'"

From BBC ● Jun. 26, 2025

Using her large social media following, Lucy says she is determined to raise awareness of what it's like to go to festivals and other big events with a stoma bag, or other accessibility needs.

From BBC ● Jun. 26, 2025

Each of these openings is called a stoma.

From Outlines of Lessons in Botany, Part I; from Seed to Leaf by Newell, Jane H.

"Doctors have told me that if they'd caught it sooner, I wouldn't have ended up the way I am, living with two stomas and being in early menopause at the age of 31."

From BBC ● Nov. 17, 2024

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 model, who made it to the final of the BBC's hit reality series, said her "main goal" after the show was to raise awareness of disabilities and break the taboo around stomas.

From BBC ● Apr. 9, 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

The vest also has a pocket on the back with extra stomas and supplies.

From BBC ● Nov. 4, 2023

As the research team explained, "Traditionally, we've had to choose between seeing the stomata or measuring their function."

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

Coincidentally, the closure of stomata also obstructs the preferred entry points for nutrient-sucking pests like spider mites.

From Science Daily ● May 3, 2024

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

When, however, the same trial is made on the upper surface of a leaf, where stomata do not occur, no such change occurs. 

From Rustic Sounds and Other Studies in Literature and Natural History by Darwin, Francis, Sir