|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes.|
|aplastic anemia (ā-plās'tĭk) Pronunciation Key
A form of anemia in which the capacity of the bone marrow to generate red blood cells is defective. Aplastic anemia may be caused by bone marrow disease or exposure to toxic agents, such as radiation, chemicals, or drugs.