Pith

1. Hence: The which contains the strength of life; the vital or essential part; concentrated force; vigor; strength; importance; as, the speech lacked pith.
2. The spinal cord; the marrow.
3. The spongy interior substance of a feather.
4. 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.
5. 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.