pith / pi[unvoicedth]/ • n. 1. soft or spongy tissue in plants or animals, in particular: ∎ spongy white tissue lining the rind of an orange, lemon, and other citrus fruits. ∎ Bot. the spongy cellular tissue in the stems and branches of many higher plants. ∎ archaic spinal marrow. 2. fig. the essence of something: the pith and core of socialism. 3. fig. forceful and concise expression: he writes with a combination of pith and exactitude. • v. [tr.] 1. dated, chiefly fig. remove the pith from. 2. rare pierce or sever the spinal cord of (an animal) so as to kill or immobilize it. DERIVATIVES: pith·less adj.
1. (or medulla) The cylinder of parenchyma tissue found in the centre of plant stems to the inside of the vascular tissue. It is light in weight and has been put to various commercial uses, notably the manufacture of pith helmets.
2. (not in scientific usage) The white tissue below the rind of many citrus fruits.
3. To destroy the central nervous system of an animal, especially a laboratory animal such as a frog, by severing its spinal cord.