(1) (Electr) A primary battery or element of a storage battery. (2) (Math) An element of an array. (3) (Comput) An elementary unit of storage in a computer. (4) (Biol) A small biological structural unit, consisting of a semiliquid living substance enclosed in a membrane and generally containing a nucleus. Note: All body tissues are composed of cells, of which there are many different kinds, including nerve cells, muscle cells, blood cells, connective tissue cells, fat cells, and others