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