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