(1) An elastic tubular channel, such as an artery, a vein, or a capillary, through which the blood circulates.

See Blood vessels

(2) All the vessels lined with endothelium through which blood circulates. A vessel in which blood circulates.The circulatory system used to transport around the body consists of many tubes that control the flow of blood around the body, these are blood vessels, consisting primarily of arteries and veins.