The word "dens" can be expressed in various synonyms such as lair, burrow, retreat, or den. A "lair" is usually a place where wild animals reside and hide themselves from predators. A "burrow" is a hole in the ground where small animals, like rabbits or foxes, can hide from danger or use as a home. A "retreat" usually refers to a place where someone goes for peace or solace away from their daily routine. Lastly, a "den" can be used interchangeably with the word "lair" but may also refer to a room or space in a house used for relaxation or privacy.