cambium

noun

Etymology: Borrowed from Late Latin cambium (“a change”), from Gaulish. Doublet of change.

1. A layer of cells between the xylem and the phloem that is responsible for the secondary growth of roots and stems.

   “During winter we perceive no change in the cells of the cambium layer, which are filled with nutritive matter […].”

2. Periosteum, a membrane that covers the outer surface of bones
3. One of the humours formerly believed to nourish the bodily organs.

   “The radical or innate is daily supplied by nourishment, which some call cambium, and make those secondary humours of ros and gluten to maintain it […]”