the soft spongy substance in the center of the stems of many plants and trees, especially those of the dicotyledonous or exogenous classes. it consists of cellular tissue.-the spongy interior substance of a feather.-the spinal cord; the marrow.-hence: the which contains the strength of life; the vital or essential part; concentrated force; vigor; strength; importance; as, the speech lacked pith.-to destroy the central nervous system of (an animal, as a frog), as by passing a stout wire or needle up and down the vertebral canal.