Definition: Medullary

Forming the central part of certain organs; relating to the spinal cord or bone marrow.

Botanical term. Medullary canal, a cylindrical cavity that occupies the centre of the stem of dicotyledonous plants.

Medullary rays, vertical blades that extend from the pith in all directions, towards the circumference of the stem, and are visible in the form of rays on the cross-section of a tree trunk.