Here's what rhymes with needlessness.
heedlessness Words that almost rhyme with needlessness
sleeplessness speechlessness ceaselessness evenness feebleness unevenness peacefulness deaconess speciousness grievousness ingeniousness covetousness treasonous dreaminess facetiousness creaminess recentness egregiousness gleefulness steaminess vehemence edematous pediments cenotaphs deceitfulness