Here's what rhymes with undeify.
                        
                        
                    
                                high  thy  vi  hi  shy  sigh  fi  hy  thigh  vie  psi  hai  cy  fy  sy  thei  phi  deify  by  my  why  die  lie  y  buy  fly  sky  guy  tie  bi  bye  chi  dye  nigh  pi  pie  spy  thai  dei  fry  ly  quae  rye  sly  ty  wir  amplify  awry  lye  mai  muy  nai  wry  kai  lai  luy  mei  tai  wai  sty  stye  slier  apply  dry  try  cry  modify  defy  notify  ply  underlie  nullify  pacify  pry  tri  trie  pri  terrify  typify  untie  edify  mollify  aquae  bonsai  ossify  spry  amebae  turfy  lanai  mummify  beatify  speechify  banzais  dandify  supply  thereby  deny  justify  rely  hereby  specify  simplify  testify  verify  butterfly  certify  purify  alibi  magnify  ratify  unify  belie  decry  pupae  amoebae  codify  dignify  overlie  ramify  acidify  firefly  mystify  retry  ultrahigh  blowfly  horrify  petrify  reunify  stupefy  overfly  scurfy  versify  barfly  prettify  shanghai  vitrify  overbuy  yuppify  identify  reply  imply  nearby  occupy  satisfy  whereby  clarify  comply  nuclei  qualify  alkali  classify  signify  glorify  goodbye  gratify  intensify  quantify  alveoli  diversify  rectify  samurai  beautify  falsify  indemnify  lullaby  solidify  termini  crucify  descry  liquefy  mortify  objectify  personify  resupply  vilify  demystify  stratify  stultify  triply  vivify  calcify  emulsify  misapply  liquify  scarify  drachmai  gentrify  ripply  stimuli  multiply  exemplify  fortify  standby  oversupply  detoxify  dragonfly  electrify  preoccupy  dissatisfy  declassify  hyperbolae  syllabify  solemnify  disqualify  reclassify  revivify  misidentify  refortify  oversimplify  cumuli  transmogrify