What is the meaning of Capillary?

Of or pertaining to hair.

Of or pertaining to a narrow tube.

Of, relating to, or caused by surface tension.

A narrow tube.

Any of the small blood vessels (from 5 to 10 micrometres/micrometers (μm) in diameter) that connect arteries to veins (They are the smallest blood vessels in the body: they convey blood between the arterioles and venules).

Source: wiktionary.org