grotto

noun6

1. •
   A small cave.
2. •
   An artificial cavern-like retreat.
3. •
   A Marian shrine, usually built in a cavern-like structure.
4. •
   A garden or roadside shrine with a small cave containing a statue of the Blessed Virgin Mary (usually Our Lady of Lourdes and sometimes paired with a water feature)
5. •
   A local organization of cavers that typically organizes trips to caves and provides information and training for caving; a caving club.

   • An earlier attempt to organize a grotto in the Indiana, PA, area in the mid-1970s failed to succeed, but from it developed the informal Chestnut Ridge Explorers Association. — 1987
6. •
   A secretive name for a local group of underground Satanists.