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