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.

---

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

---

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.

---

capillary Cultural  

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

---

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

• intercapillary
  adjective
• noncapillary
  adjective

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

“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

That energy arrives through an exceptionally dense vascular network in which each neuron is supplied by its own capillary.

From Science Daily • Oct. 30, 2025

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

But for hummingbirds, which flick their tongues 15 times per second as they drain each flower and quickly move on, capillary action just isn’t fast enough, Rico-Guevara says.

From Science Magazine • May 24, 2023

“And of course,” Rachael said distantly, “my verbal responses won’t count. It’s solely the eye-muscle and capillary reaction that you’ll use as indices. But I’ll answer; I want to go through this and—”

From "Do Androids Dream of Electric Sheep?" by Philip K. Dick

Related Words

• hair
• lode
• nerve
• seam
• stripe