When gas has fully dissolved in a liquid to the point where no more can enter, this state is called what?

The correct term for the state where gas has fully dissolved in a liquid to the point where no more can enter is saturation. In this state, the liquid has reached its maximum capacity to hold the gas under given temperature and pressure conditions. At saturation, any additional gas that might be introduced will not dissolve and may instead escape back into the atmosphere if the pressure is released, or it will form bubbles depending on the conditions.

Saturation is a critical concept in diving, as understanding this is essential for managing the risk of decompression sickness, which can occur when dissolved gases are released too quickly from the body as divers ascend. Moreover, saturation is a stable equilibrium point where the amount of gas dissolved is consistent, hence important for planning safe ascents and decompression stops during dives.