A.cave hollowed out by water, hollow rock, S.Fr.549, Pl.Phd.110a, Arist.HA548a24, al.; of a lion's den, Theoc.25.223; of the sponge-like pores of the lungs, Pl.Ti.70c, Ps.-Democr. in Hp.Ep.23; of the bronchi, Ruf.Onom.159; medullary cavity of a bone, Antyll. ap. Orib.44.20.11.
III. v. σήραγγος.