Immobilization means making something unable to move or keeping it completely still. When doctors immobilize a broken arm, they put it in a cast so the bones can heal in the correct position. The cast prevents any movement that might damage the injury further.

In nature, some animals use immobilization as a hunting strategy. A boa constrictor immobilizes its prey by wrapping around it so tightly that the animal cannot escape. Spider venom often works by immobilizing insects, paralyzing them so the spider can feed.

The word can also describe stopping something from working or functioning. A computer virus might cause the immobilization of an entire network. A snowstorm could lead to the immobilization of traffic across a city. Military forces try to immobilize enemy vehicles by damaging their engines or wheels.

When something undergoes immobilization, it goes from being active and movable to being fixed and still, whether that's a healing bone, a captured animal, or a stuck car.