reticuloendothelium

noun
re·​tic·​u·​lo·​en·​do·​the·​li·​um | \ -ˌen-də-ˈthē-lē-əm How to pronounce reticuloendothelium (audio) \
plural reticuloendothelia\ -​lē-​ə How to pronounce reticuloendothelia (audio) \

Medical Definition of reticuloendothelium

: the cells of the reticuloendothelial system regarded as a tissue