Mammoth Uncensored Word List:
144 words ending with um, 11 letters long

acroclinium animalculum antependium antheridium antirrhinum apodyterium archegonium aspergillum aspersorium bryophyllum californium candelabrum capillitium carborundum carpogonium cassiopeium clinandrium clostridium columbarium condominium copernicium corrigendum crematorium cynoglossum cypripedium definiendum desideratum diascordium dinotherium dockominium einsteinium endocardium endocranium endometrium endoneurium endothecium endothelium epigastrium equilibrium erythronium eubacterium excrementum exoperidium florilegium formicarium frigidarium gametangium gynostemium haematobium helichrysum hesperidium hippeastrum hormogonium hydrargyrum hydroxonium incunabulum insectarium intermedium interregnum intervallum intrapartum ipratropium latifundium latrocinium leprosarium livermorium lubritorium macrophylum maggotorium magisterium mediastinum mendelevium menispermum mesothelium mesothorium ministerium monochasium muscatorium nonaluminum nototherium ophidiarium organistrum ostensorium pandemonium panjandarum paramaecium paramoecium parascenium pelargonium penicillium pericardium pericranium peridesmium perimetrium perineurium peristomium perithecium peritonaeum phosphonium pittosporum planetarium podophyllum polychasium polygonatum polyzoarium positronium postscenium procerebrum proctodaeum promycelium prothallium quadrennium retinaculum roentgenium satellitium scriptorium sempervivum sempiternum sericterium sphaeridium sporogonium staminodium stylopodium subcutaneum subdelirium succedaneum superphylum suppedaneum syllabarium syncerebrum taurobolium termitarium tetrazolium tridominium ultravacuum unnilhexium ununpentium ununseptium xenodochium xeranthemum zanthoxylum zoodendrium zoogonidium zoospermium