Immobile means unable to move or be moved. When something is immobile, it stays completely still, like a statue in a park or a car stuck in deep mud with its wheels spinning uselessly.

A broken-down truck sitting on the side of the highway is immobile until a tow truck arrives. A chess piece becomes immobile when it's blocked in by other pieces with nowhere legal to go. After spraining your ankle badly, your foot might be immobile for days while it heals, wrapped up and needing to stay still.

Immobile can describe physical things that won't budge, but also situations where someone feels stuck. A student might feel immobile when facing a really hard problem, frozen and unsure how to start. The word suggests complete stillness, an absolute lack of movement. A turtle moves slowly, but it's not immobile. A boulder weighing several tons sitting in your backyard? That's immobile unless you bring in serious equipment.

When something becomes immobile that should be moving, like traffic during a major accident, we say it's immobilized. The key idea is being completely still.