Here's what rhymes with downness.
brownness Words that almost rhyme with downness
aureus ous bounteous doubtless boundless countess prowess loudness foulness stoutness outface owlets countless soundness roundness soundless devoutness roundups allowance cloudless groundless leprous accountants groundnuts thousandths unsoundness mountebanks profoundness viscountess announcements endowments denouncements pronouncements