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 vital substance in the human body. It is mainly composed of water, blood cells and other elements and substances. It has many functions in the body and some of these functions are carried out by blood cells. But unlike normal body cells, blood cells are quite different in being isolated (not packed to form a tissue, free moving).