Capillary
WordNet
adjective
(1) Long and slender with a very small internal diameter
"A capillary tube"
(2) Of or relating to hair
noun
(3) A tube of small internal diameter; holds liquid by capillary action
(4) Any of the minute blood vessels connecting arterioles with venules
WiktionaryText
Etymology
From < < .
Noun
- Any of the small blood vessels that connect arteries to veins. Their walls are composed of a single layer of cells which allows molecules such as oxygen, water and lipids to pass through them by diffusion and enter the tissues. Waste products such as carbon dioxide and urea can diffuse back into the blood to be carried away for removal from the body.