Here's what rhymes with nntum.
erratum Words that almost rhyme with nntum
mutton button piton nubbin sudden glutton dudgeon unbutton dubbin exciton globin bludgeon scutcheon androgen escutcheon bellybutton ahem custom caecum accustom cementum buxom buncombe bunkum dumdum humdrum jejunum corundum secundum conundrum colostrum carborundum