Capillary

Resembling a hair; fine; minute; very slender; having minute tubes or interspaces; having very small bore; as, the capillary vessels of animals and plants.

Pertaining to capillary tubes or vessels; as, capillary action.

A tube or vessel, extremely fine or minute.

A minute, thin-walled vessel; particularly one of the smallest blood vessels connecting arteries and veins, but used also for the smallest lymphatic and biliary vessels.

any of the minute blood vessels connecting arterioles with venules