Center letter: r
Outer letter: g i m n o u
Answers (57):
  mourning
  rumoring
  unmooring
  gorging
  gorgon
  goring
  grim
  grin
  grinning
  grog
  groin
  groom
  grooming
  guru
  ignoring
  inuring
  inurn
  inurning
  iron
  ironing
  minor
  minoring
  mirin
  miring
  mirror
  mirroring
  moor
  mooring
  morn
  morning
  moron
  mourn
  murmur
  murmuring
  nigiri
  noir
  nori
  norm
  origin
  rigging
  rigor
  rimming
  ring
  ringing
  room
  rooming
  rouging
  ruin
  ruing
  ruining
  rumor
  rung
  running
  unmoor
  unrig
  unrigging
  urging