designating or of the system of macrophages found in the bone marrow, liver, spleen, etc., including all the phagocytic cells except the granular leukocytes: they can take up certain dyes, bacteria, etc.
See reticuloendothelial in American Heritage Dictionary 4
(rĭ-tĭkˌyə-lō-ĕnˌdə-thēˈlē-əl)
noun
Of, relating to, or being the widely diffused bodily system constituting all phagocytic cells except certain white blood cells.