Here's what rhymes with unforgiveness.
                        
                        
                    
                                forgiveness  Words that almost rhyme with unforgiveness
business  stiffness  bismuth  agribusiness  witness  thickness  fitness  sickness  richness  quickness  bigness  dimness  minutes  vicious  stillness  citrus  fearless  eyewitness  grimace  rivets  pivots  sinless  sinuous  cirrus  nimbus  villus  witless  religious  limits  bishops  visits  clearance  mistress  digits  tickets  auspicious  viscous  assiduous  listless  litmus  pickets  strictness  swiftness  thickets  billets  crickets  discus  hillocks  officious  pittance  unfitness  beardless  bigots  litigious  pickups  riddance  wickets  windlass  windless  wingless  distance  appearance  spirits  ambitious  exhibits  suspicious  coherence  delicious  fictitious  judicious  malicious  pernicious  prodigious  bacillus  biscuits  brilliance  capricious  hindrance  archbishops  elicits  frigates  nutritious  papyrus  propitious  seditious  trinkets  avaricious  cystitis  eucalyptus  factitious  irreligious  remittance  resistless  triplets  profitless  snippets  solicits  existence  assistance  resistance  adherence  inhibits  shipments  admittance  pigments  prestigious  prohibits  adventitious  diffidence  meniscus  reappearance  indigence  repetitious  surreptitious  hibiscus  mastitis  nonreligious  unambitious  unpropitious  coefficients  assistants  commitments  insistence  persistence  subsistence  adherents  superstitious  contingents  distinctness  reminiscence  consistence  expeditious  incoherence  injudicious  interference  disappearance  perseverance  coexistence  delinquents  infringements  nonexistence  transmittance  endearments  enlistments  noninterference