crypt

plural crypts

1. archaicA cave or cavern.First known use 15th c.
2. An underground vault.
   1. Especially: one beneath a church that is used as a burial chamber.First known use 16th c.

      Near-synonyms: vault, tomb, sepulchre, sepulcher

      2 more examples

      She turned and waved a hand to him, she cried a word, but he didn't hear it, it was a lost word. A sable wraith she was in the parkland, fading away into the dolorous crypt of winter.

      1922, Michael Arlen, “3/2/1”, in “Piracy”: A Romantic Chronicle of These Days

      On its arrival at Bank, incidentally, the City & South London's directors had threatened to demolish the church of St Mary Woolnoth, but after a public outcry the company built its station in the crypt of the church, the bodies being transferred [...]. Therefore St Mary Woolnoth doesn't have a crypt. Or you could say that its crypt is Bank station.

      2012, Andrew Martin, Underground Overground: A passenger's history of the Tube, Profile Books, →ISBN, page 106

      Synonyms: vault, tomb, sepulchre, sepulcher

3. anatomyA small pit or cavity in the surface of an organ or other structure.First known use 19th c.

   Near-synonyms: fovea, fossa

   1 more example

   Sometimes, too much foreign material can get caught in the crypts, leading to frequent infections.

   2015, Giulia Enders, translated by David Shaw, Gut, Scribe, published 2016, page 25

   Synonyms: fovea, fossa

4. biologyAny of the genus Cryptocoryne of aquatic plants of southern and southeastern Asia.
5. biologyAny of the genus Cryptopus of orchids of Madagascar and Mauritius.