What is the phase change called when a gas turns into a solid?

The phase change when a gas turns into a solid is called deposition. During deposition, molecules in the gas phase lose energy and transition directly into a solid state without first becoming liquid. This process is exemplified by phenomena such as frost forming on surfaces in cold weather, where water vapor in the air changes directly into ice.

Condensation refers to the process where gas turns into a liquid, often seen with water vapor forming droplets on a cool surface. Sublimation is the reverse process of deposition, where a solid transitions directly into a gas, like dry ice turning into carbon dioxide gas without becoming liquid first. Freezing is the transition of a liquid into a solid, which occurs when a liquid loses enough energy. Thus, deposition specifically describes the direct change from a gas to a solid, and it is the correct term for this phase transition.