mixonephridium
/ˌmɪksəʊnɪˈfrɪdɪəm/Zoology
noun
In many polychaetes: a combined nephridium and coelomoduct in which the coelomic end of the nephridium is completely fused with the coelomostome.
Origin
1940s. From mixo- + nephridium. Compare earlier nephromixium, protonephridium, metanephridium.