\Cam"bi*um\, n. [LL. cambium exchange, fr. L. cambire to
exchange. It was supposed that cambium was sap changing into
wood.]
1. (Bot.) A series of formative cells lying outside of the
   wood proper and inside of the inner bark. The growth of
   new wood takes place in the cambium, which is very soft.
2. (Med.) A fancied nutritive juice, formerly supposed to
   originate in the blood, to repair losses of the system,
   and to promote its increase. --Dunglison.