Here's what rhymes with octogenarian.
                        
                        
                    
                                carrion  ovarian  clarion  agrarian  barbarian  sectarian  trinitarian  librarian  totalitarian  antiquarian  libertarian  vegetarian  disciplinarian  veterinarian  centenarian  sanitarian  seminarian  nonagenarian  vulgarian  cnidarian  authoritarian  utilitarian  egalitarian  proletarian  latitudinarian  septuagenarian  communitarian  parliamentarian  nonsectarian  valetudinarian  sexagenarian  humanitarian  Words that almost rhyme with octogenarian
barium  chameleon  honorarium  aquarium  vivarium  nobelium  sanitarium  planetarium  ferryman  ferrymen  lesbian  thespian  pedestrian  equestrian  vestrymen  vestryman