Here's what rhymes with underdigestion.
                        
                        
                    
                                digestion  ingestion  question  suggestion  congestion  indigestion  autosuggestion  Words that almost rhyme with underdigestion
destine  intestine  intention  tension  chairman  detection  lesson  pension  detention  lessen  ejection  dejection  distention  pepsin  abstention  beckon  deaden  gentian  penman  pennon  bellman  deafen  indention  pressman  attention  direction  section  election  seven  depression  heaven  mention  session  dimension  eleven  injection  objection  rebellion  rejection  weapon  deception  erection  lemon  reckon  resin  tendon  cession  defection  dissension  dentin  distension  headman  inattention  leaden  leaven  lengthen  melon  felon  headmen  henchmen  heron  pectin  henchman  penguin  stepson  redden  vegan  hessian  kelvin  hellion  nelson  protection  exception  extension  impression  infection  intervention  perception  possession  affection  correction  inspection  invention  perfection  reception  brethren  oppression  projection  redemption  retention  strengthen  threaten  deflection  dissection  inception  obsession  recession  resection  secession  subjection  ascension  pretension  indirection  sexton  abjection  chevron  freshen  lepton  bisection  hempen  subvention  headsman  gremlin  expression  collection  connection  profession  selection  aggression  discretion  prevention  accession  apprehension  connexion  contention  hypertension  intersection  procession  repression  suppression  suspension  complexion  exemption  insurrection  freshman  imperfection  inflection  intercession  digression  disaffection  reelection  declension  dispossession  interception  preemption  redirection  inflexion  interjection  misdirection  delicatessen  prepossession  refection  supervention  conception  reflection  compression  convention  succession  concession  confession  progression  regression  resurrection  convection  introspection  predilection  condescension  contravention  disinfection  interconnection  disconnection  reflexion  watermelon  circumvention  concretion  confection  nonintervention  reinfection  reinvention  rhododendron  repossession  reprehension  selectman  comprehension  recollection  contraception  transgression  decompression  indiscretion  circumspection  retrospection  nonaggression  genuflection  misconception  misapprehension  retrogression  preconception  incomprehension