Center letter: u
Outer letter: b d g i l n
Answers (45):
  building
  bundling
  unbuilding
  unbundling
  bubbling
  budding
  budging
  bugging
  bugling
  build
  bulb
  bulging
  bull
  bung
  bungling
  dubbing
  dull
  dulling
  dung
  dunning
  glug
  glugging
  gluing
  guiding
  guild
  gull
  gulling
  gunning
  indulging
  linguini
  lubing
  lugging
  luging
  lull
  lulling
  lulu
  lung
  lunging
  nubbin
  nudging
  null
  unbind
  unbinding
  unbuild
  undid