n.1 the inner region of certain organs or tissues usu. when it is distinguishable from the outer region or cortex, as in hair or a kidney.
2 the myelin layer of certain nerve fibres.
3 the soft internal tissue of plants.
Phrases and idioms:
medulla oblongata the continuation of the spinal cord within the skull, forming the lowest part of the brain stem.
Derivatives:
medullary adj.
Etymology: L, pith, marrow, prob. rel. to medius middle