Center letter: n
Outer letter: a f i l p u
Answers (32):
  painful
  anal
  annal
  annual
  annul
  annuli
  apian
  faun
  fauna
  faunal
  final
  finial
  flan
  infill
  lain
  lanai
  luna
  lunula
  naan
  naif
  nail
  nana
  null
  pain
  panini
  pinup
  pippin
  plain
  plan
  puffin
  ulna
  unpin