venous blood; dark blood
Refers to blood that is dark red or purplish because it is deoxygenated, as opposed to bright red arterial blood. Used in medical and everyday contexts.
Venous blood flows through the veins.
Dark blood was coming from the wound.
Compound of 黒 (くろ, 'black') and 血 (ち, 'blood'), literally 'black blood', referring to the darker color of deoxygenated blood.