The term myeloid is an adjective that relates to the granulocyte precursor cell in bone marrow or spinal cord, or a resemblance to the marrow or spinal cord. For example, myeloid leukemia is leukemia that arises from abnormal growth in the blood-forming tissue of the bone marrow.1
In hematopoiesis, the term "myeloid cell" describes any blood cell that is not a lymphocyte. This terminology is often seen when classifying cancers, especially leukemia.
The term should not be confused with "myelin", which is an insulating layer covering the axons of many neurons.
Macpherson, Gordon (2002). Black's Medical Dictionary. London: A & C Black Publishers. ISBN 02713654422 .