noun a tube or vessel, extremely fine or minute.
2. capillary ·adj pertaining to capillary tubes or vessels; as, capillary action.
3. capillary ·adj resembling a hair; fine; minute; very slender; having minute tubes or interspaces; having very small bore; as, the capillary vessels of animals and plants.
4. capillary ·noun 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.