Den /(dĕn)/

Den

n.
  1. A small cavern or hollow place in the side of a hill, or among rocks; esp., a cave used by a wild beast for shelter or concealment; as, a lion's den; a den of robbers.
  2. A squalid place of resort; a wretched dwelling place; a haunt; as, a den of vice.
  3. Any snug or close retreat where one goes to be alone. [Colloq.]
  4. A narrow glen; a ravine; a dell. [Old Eng. & Scotch]

Den

v. i.
  1. To live in, or as in, a den.
    The sluggish salvages that den below.