Center letter: a
Outer letter: b c k m o r
Answers (57):
  backroom
  aback
  ammo
  amok
  arbor
  arco
  armor
  aroma
  baba
  babka
  back
  backcomb
  bamboo
  baobab
  barb
  barback
  barbacoa
  bark
  barrack
  barroom
  boar
  boba
  bookmark
  bookrack
  cacao
  camo
  carb
  carob
  carom
  cobra
  coca
  cocoa
  coma
  comma
  crab
  crack
  cram
  croak
  kabob
  kaboom
  karma
  korma
  macro
  mako
  mama
  mamba
  mambo
  mamma
  maraca
  mark
  marm
  momma
  okra
  orca
  rack
  roam
  roar