grotto

from WordNet (r) 3.0 (2006)

grotto
    n 1: a small cave (usually with attractive features) [syn:
         {grotto}, {grot}]

from The Collaborative International Dictionary of English v.0.48

grotto \grot"to\ (gr[o^]t"t[-o]), n.; pl. {Grottoes}
   (gr[o^]t"t[=o]z). [Formerly grotta, fr. It. grotta, LL.
   grupta, fr. L. crypta a concealed subterranean passage,
   vault, cavern, Gr. kry`pth, fr. krypto`s concealed, fr.
   kry`ptein to conceal. Cf. {Grot}, {Crypt}.]
   A natural covered opening in the earth; a cave; also, an
   artificial recess, cave, or cavernlike apartment.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

18 Moby Thesaurus words for "grotto":
      abri, antre, bunker, burrow, cave, cavern, cove, dugout, foxhole,
      grot, hole, lair, sewer, subterrane, subterranean, subway, tunnel,
      warren