myeloidPronunciation: /ˈmʌɪəlɔɪd/Definition of myeloid adjective 1relating to bone marrow. (of leukaemia) characterized by the proliferation of cells originating in the bone marrow. 2relating to the spinal cord. Origin: mid 19th century: from Greek muelos 'marrow' + -oidmyeloid in other Oxford dictionaries Definition of myeloid in the US English dictionary