Here's what rhymes with undecomposing.
                        
                        
                    
                                composing  posing  dozing  imposing  opposing  decomposing  nosing  hosing  apposing  closing  supposing  reposing  deposing  purposing  recomposing  unimposing  exposing  proposing  disposing  enclosing  inclosing  interposing  juxtaposing  superimposing  transposing  disclosing  presupposing  superposing  predisposing  foreclosing  Words that almost rhyme with undecomposing
dosing  joshing  loathing  roving  loafing  unloving  clothing  unfrozen  grossing  engrossing  underclothing  overdosing  diagnosing  bowing  choking  joking  polling  boating  bowling  poking  towing  poaching  tolling  condoning  doting  toning  toting  boding  doling  poling  toeing  boning  condoling  doming  going  showing  knowing  controlling  loading  rolling  voting  blowing  coating  coding  coping  hoping  noting  sewing  boasting  coaching  posting  probing  rowing  soaking  sowing  unloading  zoning  combing  consoling  foaming  moaning  roaming  atoning  bolting  coking  hoeing  homing  jolting  lowing  bloating  bowstring  cajoling  droning  goading  honing  loaning  phoning  roping  shoeing  stoning  stowing  toasting  trolling  unknowing  unrolling  broaching  holing  intoning  moping  shoaling  stoking  yoking  soaping  foaling  meowing  paroling  growing  holding  approaching  floating  flowing  smoking  throwing  undergoing  encoding  folding  glowing  quoting  sloping  unfolding  cloning  denoting  devoting  groping  invoking  molding  moulding  slowing  coasting  decoding  evoking  groaning  growling  hosting  roasting  stroking  strolling  coaxing  croaking  crowing  enrolling  eroding  snowing  bemoaning  buttoning  gloating  moulting  cloaking  connoting  disowning  gloaming  molting  nonvoting  scoping  unbuttoning  convoking  ghosting  imploding  ingrowing  offloading  buttonholing  demoting  emoting  hoaxing  kowtowing  promoting  provoking  upholding  beholding  bestowing  encroaching  foreboding  patrolling  scolding  ennobling  extolling  reproaching  reloading  revoking  scrolling  enfolding  oceangoing  rezoning  disrobing  infolding  proroguing  blazoning  chaperoning  honeycombing  pawnbroking  pigeonholing  snowshoeing  foregoing  overflowing  revolting  exploding  postponing  easygoing  overloading  overthrowing  telephoning  telescoping  forgoing  logrolling  nonsmoking  wainscoting  refolding  remolding  remoulding  cuckolding  foreknowing  misquoting  overgrowing  withholding