Definition - What does Sublimation mean?
Sublimation is a phase of transition in the state of matter from a solid to a gas. In making this transition, the solid does not pass through a liquid state. The transition from solid to gas is facilitated by temperature and atmospheric pressure. Sublimation occurs when the temperature and pressure of a substance drops below its triple point, which is the point at which it can exist at solid, liquid and gaseous forms.
Safeopedia explains Sublimation
Sublimation occurs with solid water when it drops below its triple point. A temperature increase will see it change directly into a gas without passing through the liquid state. Carbon dioxide has a triple point at a pressure higher than 1 atmospheric pressure. At the earth's standard atmosphere pressure, carbon dioxide will sublimate as it heats from a solid to a gas.