medulla medulla /mɪˈduːlə/

noun

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