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 cell. n. Any of the cells contained in blood; an erythrocyte or leukocyte; a blood corpuscle. blood cell. n. (Physiology) any of the cells that circulate in the blood. See erythrocyte, leucocyte.