of or pertaining to a vein or veins; as, the venous circulation of the blood.-contained in the veins, or having the same qualities as if contained in the veins, that is, having a dark bluish color and containing an insufficient amount of oxygen so as no longer to be fit for oxygenating the tissues; -- said of the blood, and opposed to arterial.-marked with veins; veined; as, a venous leaf.