n. A hollow place in the earth or in a rock; a cave, pit, or subterraneous recess, used for concealment, shelter, protection, or security: as, a lion's den.n. A grave.n. Any squalid place of resort or residence; a haunt: always used in a bad sense: as, dens of misery.n. A small or secluded private apartment; a retreat for work or leisure.To dwell in or as if in a den.n. A narrow valley; a glen; a dell.n. A corruption of even in the phrase good even.