n. 1. Physical or mental weariness resulting from effort or activity. 2. Something, such as tiring effort or activity, that causes tiredness or weariness: the fatigue of a long hike. 3. Physiology The decreased capacity or complete inability of an organism, organ, or part to function normally because of excessive stimulation or prolonged exertion. 4.
blood - the fluid (red in vertebrates) that is pumped through the body by the heart and contains plasma, blood cells, and platelets; blood carries oxygen and nutrients to the tissues and carries away waste products; the ancients believed that blood was the seat of the emotions
Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.