Here's what rhymes with octadrachm.
drachm Words that almost rhyme with octadrachm
problem blossom bottom column solemn forum boredom mortem balsam condom dorsum sorghum bonum rostrum wampum flotsam possum thraldom foursome slalom thralldom carom cockscomb quantum decorum quorum nostrum metronome opossum stardom gastronome postpartum falciparum macrocosm sugarplum microcosm