capillary

American  

[kap-uh-ler-ee] / ˈkæp əˌlɛr i /

adjective

1. pertaining to or occurring in or as if in a tube of fine bore.

2. resembling a strand of hair; hairlike.

3. Physics.

   1. pertaining to capillarity.

   2. of or relating to the apparent attraction or repulsion between a liquid and a solid, observed in capillarity.

4. Anatomy. pertaining to a capillary or capillaries.

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noun

capillaries plural

1. Anatomy. one of the minute blood vessels between the terminations of the arteries and the beginnings of the veins.

2. Also called capillary tube.  a tube with a small bore.

capillary British  

/ kəˈpɪlərɪ /

adjective

1. resembling a hair; slender

2. (of tubes) having a fine bore

3. anatomy of or relating to any of the delicate thin-walled blood vessels that form an interconnecting network between the arterioles and the venules

4. physics of or relating to capillarity

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noun

1. anatomy any of the capillary blood vessels

2. a fine hole or narrow passage in any substance

capillary Scientific  

/ kăp′ə-lĕr′ē /

1. Any of the tiny blood vessels that connect the smallest arteries (arterioles) to the smallest veins (venules). Capillaries form a network throughout the body for the exchange of oxygen, metabolic waste products, and carbon dioxide between blood and tissue cells.

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capillary Cultural  

1. A thin tube, such as a blood vessel or a straw, through which fluids flow.

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Discover More

The interaction between the fluid and the vessel walls produces a force that can lift the fluid up into the tube, a phenomenon known as capillary action.

Other Word Forms

Derived Forms

• intercapillary
  adjective
• noncapillary
  adjective

Inflected Forms

Nouns

• capillaries
  plural

Etymology

Origin of capillary

1570–80; capill ( ar ) (obsolete, < Latin capillāris pertaining to hair, equivalent to capill ( us ) hair + -āris -ar ¹ ) + -ary

Explanation

You are probably most familiar with the word capillary as a minute vessel that transports blood to larger vessels in the body, but a capillary can actually mean any tiny tubelike device that moves a liquid from point to point. Capillary comes from the Latin word capillaris, meaning "of or resembling hair." The meaning stems from the tiny, hairlike diameter of a capillary. While capillary is usually used as a noun, the word also is used as an adjective, as in "capillary action," in which a liquid is moved along — even upward, against gravity — as the liquid is attracted to the internal surface of the capillaries.

Example Sentences

See Examples For:

capillary capillaries

“Renewables require a completely different kind of grid,” says Luca Moro, chief investment officer at energy-focused fund SpesX, “a capillary system instead of one-way transmission from a power plant.”

From Barron's ● May 27, 2026

This effect is also seen in the microcapillaries of plants, where water transport occurs thanks to a combination of capillary pressure and natural evaporation.

From Science Daily ● Mar. 6, 2024

Water can work its way under the door threshold via capillary attraction, wind or even negative slope on the exterior landing, causing water to run toward the room.

From Seattle Times ● Sep. 26, 2023

Researchers used to assume these birds relied on capillary action—the tendency of a liquid to flow up a narrow tube—to take in nectar.

From Science Magazine ● May 24, 2023

Light flickered on bits of ruby glass and on sensitive capillary hairs in the nylon-brushed nostrils of the creature that quivered gently, gently, gently, its eight legs spidered under it on rubber-padded paws.

From "Fahrenheit 451" by Ray Bradbury

Scientists estimate the brain contains roughly one billion capillaries, with nearly every neuron connected to its own blood supply.

From Science Daily ● May 17, 2026

“It’s searing pain from all the lactic acid. It floods your system. You blow capillaries in your eyes, you throw up after races,” said Cheek, now an NBC analyst.

From The Wall Street Journal ● Feb. 21, 2026

If done properly, it's unlikely to cause you any harm, but Tina warns that "too much pressure can cause bruising or broken capillaries, so be gentle".

From BBC ● Feb. 16, 2026

Researchers hope these artificial capillaries will aid in the development of better snakebite treatments while lowering the dependence on animal models.

From Science Magazine ● Jun. 5, 2024

The mosaic thickens and throws more clots, and the clots drift through the bloodstream into the small capillaries, where they get stuck.

From "The Hot Zone" by Richard Preston

Related Words

• hair
• lode
• nerve
• seam
• stripe