ribat

noun6

1. •
   (historical) A border or frontier guardpost.
2. •
   A Sufi monastery.
3. •
   (historical) An Islamic convent.
4. •
   (figurative) The duty of all Muslims to defend and/or retake Islamic lands.
5. •
   (historical) The duty of some men to serve at such posts.
6. •
   (historical) A caravanserai or inn in, converted from, or resembling such a guardpost.