Center letter: d
Outer letter: g h n o r u
Answers (27):
  groundhog
  dodo
  doggo
  dong
  donor
  door
  dough
  dour
  drug
  dugong
  dung
  dunno
  good
  gourd
  ground
  hood
  hoodoo
  hound
  nunhood
  odor
  rondo
  rood
  round
  udon
  undo
  unground
  unhood