Webster's Revised Unabridged Dictionary · 1913

Pith

Pith , noun

[Anglo-Saxon pi{not transcribed}a; akin to Dutch pit pith, kernel, LG. peddik. Compare Pit a kernel.]

1.
(Botany) 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.
2.
(a) (Zoology) The spongy interior substance of a feather.
(b)
(Zoology) The spinal cord; the marrow.
3.
Hence: The which contains the strength of life; the vital or essential part; concentrated force; vigor; strength; importance; as, the speech lacked pith.
Enterprises of great pith and moment. — Shakespeare
Collocations (1)
Pith paper , Same as Rice paper, under Rice.

Pith , transitive verb

(Physiology) 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.