A cage is an enclosure made of bars or wire mesh that confines an animal or person while still allowing air and light to pass through. Unlike a solid box, a cage's open structure lets you see inside and lets the occupant see out. Zoos keep lions in cages (though modern zoos prefer larger, more natural enclosures). Pet owners might keep hamsters, birds, or rabbits in cages. The bars or mesh are strong enough to prevent escape but spaced to allow feeding and observation.

The word carries a feeling of confinement and restriction. When someone says they feel caged in, they mean they feel trapped or unable to move freely, even if they're not literally behind bars. A student stuck inside on a beautiful day might feel caged by classroom walls. Basketball players talk about the cage, an old nickname for the court that came from when early indoor games were played inside wire mesh enclosures to keep the ball in play and protect spectators.

The verb form means to confine or trap: you might cage a wild animal while it heals from an injury. Because cages represent a loss of freedom, freeing something from a cage can feel powerful in stories like Born Free, where lions return to the wild.