Here's what rhymes with ossarium.
                        
                        
                    
                                barium  honorarium  vivarium  aquarium  sanitarium  planetarium  Words that almost rhyme with ossarium
ovarian  carrion  clarion  agrarian  barbarian  sectarian  vulgarian  nobelium  librarian  vegetarian  chameleon  sanitarian  seminarian  cnidarian  authoritarian  egalitarian  antiquarian  libertarian  veterinarian  nonsectarian  centenarian  proletarian  totalitarian  trinitarian  octogenarian  nonagenarian  sexagenarian  humanitarian  utilitarian  disciplinarian  communitarian  parliamentarian  latitudinarian  septuagenarian  valetudinarian  fermium  gentium  requiem  biennium  millennium  proscenium  lutetium  lawrencium  technetium  quadrennium  compendium  endometrium