Liquid that flows in the veins, arteries and capillaries of a living creature. Contains plasma (the liquid which carries the red and white blood cells), red blood cells (these carry oxygen and other important resources to most* parts of the body) and white blood cells (these protect the body from viruses and bacteria). Blood is pumped around the body by the heart. The lungs put oxygen into the bloodstream, and the digestive system puts important nutrients etc. into the bloodstream. The liver filters blood, which is why many alchohol related problems include blood poisoning, liver disease etc.
also a gang who cant get up and realise that their definitions need spellcheck.
*i say most, because blood does not flow in already dead parts of your body, such as the hair and nails