What is pith? How to use in English

The word "pith" has its roots in the Old English word "pyth," which meant "cork" or "inner bark." This word is believed to have originated from the Old Norse word "pypr," which meant "inner bark" or "spongy wood." In Old English, "pyth" was used to refer to the soft, spongy material found inside the stems and trunks of plants, such as bamboo or Ensete (a type of banana plant), as well as to the inner bark of trees like birch and willow. Over time, the meaning of "pyth" and its derivatives evolved to include similar spongy or fluffy materials in various contexts. For example, the Latin word "pitus" could refer to the woolly undercoat of animals, as well as the soft inner part of fruits like coconuts and pineapples. In modern English, "pith" is used primarily to refer to the soft, spongy inner core of plants, such as the carpels of flowers or the central stem of various plants like sunflowers and thistles. It is also sometimes used as a literary or figurative term to describe the essence or core of something, such as the "pith" or "gist" of an argument or idea.