Here's what rhymes with dementedness.
contentedness Words that almost rhyme with dementedness
inventiveness effectiveness attentiveness connectedness defensiveness tenseness defectiveness restiveness deceptiveness denseness inattentiveness intensiveness pensiveness festiveness selfishness ineffectiveness offensiveness perceptiveness receptiveness disconnectedness retentiveness devilishness garishness inoffensiveness bearishness hellishness residence penitence reticence unselfishness impressiveness possessiveness extensiveness protectiveness apprehensiveness expensiveness objectiveness scarceness caribous residents aggressiveness suggestiveness headmistress oppressiveness unexpectedness celibates hesitance fetishists obsessiveness inexpensiveness expressiveness progressiveness repressiveness comprehensiveness embellishments collectivists counterintelligence