medulla
(noun)
noun
1. a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers
Similar word(s): myelin, myeline
Definition categories: substance, fat
2. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
- the medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning
Similar word(s): bulb
Definition categories: body
3. the inner part of an organ or structure in plant or animal
Definition categories: body