Literally meaning: "inflammation of bone marow"
Origin: Anc Greek
μυελός/myelos(=bone marow, core)>μύω/myo(=be enclosed)
-ίτις (modern Greek -ίτιδα)/-ites (= suffix which is used with the feminine noun η νόσος/ e nosos=disease), denoting “inflammation of”.
Myelitis is a inflammation of the spinal cord.