Center letter: a
Outer letter: b c d k o r
Answers (51):
  backboard
  backdoor
  corkboard
  aback
  aboard
  abracadabra
  abroad
  accord
  adobo
  arbor
  arco
  ardor
  baba
  babka
  back
  baobab
  barb
  barback
  barbacoa
  bard
  bark
  barrack
  boar
  board
  boba
  bookrack
  brad
  broad
  cacao
  carb
  card
  cardboard
  carob
  cobra
  coca
  cocoa
  coda
  crab
  crack
  croak
  dark
  doodad
  dorado
  drab
  kabob
  okra
  orca
  rack
  radar
  road
  roar