Center letter: d
Outer letter: a b o r t u
Answers (35):
  outboard
  troubadour
  aboard
  abroad
  adobo
  ardor
  bard
  baud
  board
  brad
  broad
  brood
  dart
  dartboard
  data
  daub
  dodo
  doodad
  door
  dorado
  dotard
  doubt
  dour
  drab
  drat
  drub
  odor
  outdo
  outdoor
  radar
  road
  rood
  tabard
  toad
  trod