Cage

From Old French cage, from Latin cavea.

Full definition of cage

(plural cages)

an enclosure made of bars, normally to hold animals.We keep a bird in a cage.The tigers are in a cage to protect the public.The most dangerous prisoners are locked away in a cage.
the passenger compartment of a lift
(hockey, water polo) the goal.
(US derogatory slang) automobile
(figuratively) Something that hinders freedom.
(athletics) The area from which competitors throw a discus or hammer.
(obsolete) A place of confinement for malefactors.

An outer framework of timber, enclosing something within it.the cage of a staircase
(engineering) A skeleton frame to limit the motion of a loose piece, such as a ball valve.
A wirework strainer, used in connection with pumps and pipes.
(mining) The drum on which the rope is wound in a hoisting whim.
(baseball) The catcher's wire mask.

2013, Henry Petroski, Geothermal Energy, Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame. With more settled people, animals were harnessed to capstans or caged in treadmills to turn grist into meal.

To keep in a cage.
To track individual responses to direct mail, either (advertising) to maintain and develop mailing lists or (politics) to identify people who are not eligible to vote because they do not reside at the registered addresses.
(figuratively) To restrict someone's movement or creativity.