Center letter: p
Outer letter: d e i n o w
Answers (55):
  pinewood
  deep
  deepen
  deepened
  depend
  depended
  dipped
  dope
  doped
  epee
  epode
  ninepin
  nipped
  nope
  open
  opened
  opine
  opined
  opinion
  opioid
  peed
  peen
  peep
  peeped
  peewee
  pend
  pended
  penne
  penned
  peon
  pepped
  pewee
  pied
  pine
  pined
  pinion
  pinioned
  pinned
  pinniped
  pipe
  piped
  pippin
  pond
  pone
  ponied
  poop
  pooped
  pope
  popped
  powwow
  weep
  weepie
  windpipe
  wipe
  wiped