The Collaborative International Dictionary of English v.0.48:

Sanctuary \Sanc"tu*a*ry\, n.; pl. Sanctuaries. [OE.
   seintuarie, OF. saintuaire, F. sanctuaire, fr. L.
   sanctuarium, from sanctus sacred, holy. See Saint.]
   A sacred place; a consecrated spot; a holy and inviolable
   site. Hence, specifically:
   (a) The most retired part of the temple at Jerusalem, called
       the Holy of Holies, in which was kept the ark of the
       covenant, and into which no person was permitted to enter
       except the high priest, and he only once a year, to
       intercede for the people; also, the most sacred part of
       the tabernacle; also, the temple at Jerusalem.
   (b) (Arch.) The most sacred part of any religious building,
       esp. that part of a Christian church in which the altar
       is placed.
   (c) A house consecrated to the worship of God; a place where
       divine service is performed; a church, temple, or other
       place of worship.
   (d) A sacred and inviolable asylum; a place of refuge and
       protection; shelter; refuge; protection.
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             These laws, whoever made them, bestowed on temples
             the privilege of sanctuary.          --Milton.
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             The admirable works of painting were made fuel for
             the fire; but some relics of it took sanctuary
             under ground, and escaped the common destiny.
                                                  --Dryden.
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