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