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